diff --git a/compiler/src/dotty/tools/dotc/core/JavaNullInterop.scala b/compiler/src/dotty/tools/dotc/core/JavaNullInterop.scala
index 37f32a9b2b16..c1b3174397f6 100644
--- a/compiler/src/dotty/tools/dotc/core/JavaNullInterop.scala
+++ b/compiler/src/dotty/tools/dotc/core/JavaNullInterop.scala
@@ -114,7 +114,7 @@ object JavaNullInterop {
           // This is because `setNames(null)` passes as argument a single-element array containing the value `null`,
           // and not a `null` array.
           || !ctx.flexibleTypes && tp.isRef(defn.RepeatedParamClass)
-        case _ => true
+        case _ => false
       }))
 
     override def apply(tp: Type): Type = tp match {
diff --git a/compiler/src/dotty/tools/dotc/typer/Applications.scala b/compiler/src/dotty/tools/dotc/typer/Applications.scala
index 9501e51aeb6f..2260a666bb1b 100644
--- a/compiler/src/dotty/tools/dotc/typer/Applications.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Applications.scala
@@ -645,14 +645,15 @@ trait Applications extends Compatibility {
               missingArg(n)
           }
 
-          if (formal.isRepeatedParam)
+          val formal1 = formal.stripFlexible
+          if (formal1.isRepeatedParam)
             args match {
               case arg :: Nil if isVarArg(arg) =>
                 addTyped(arg)
               case (arg @ Typed(Literal(Constant(null)), _)) :: Nil if ctx.isAfterTyper =>
                 addTyped(arg)
               case _ =>
-                val elemFormal = formal.widenExpr.argTypesLo.head
+                val elemFormal = formal1.widenExpr.argTypesLo.head
                 val typedArgs =
                   harmonic(harmonizeArgs, elemFormal) {
                     args.map { arg =>
diff --git a/tests/explicit-nulls/flexible-types/common/interop-propagate.scala b/tests/explicit-nulls/flexible-types/common/interop-propagate.scala
index 9be5ed26d8e3..40eb12dd287c 100644
--- a/tests/explicit-nulls/flexible-types/common/interop-propagate.scala
+++ b/tests/explicit-nulls/flexible-types/common/interop-propagate.scala
@@ -3,16 +3,16 @@
 
   // Test that type mapping works with flexible types.
   val ll: ArrayList[ArrayList[ArrayList[String]]] = new ArrayList[ArrayList[ArrayList[String]]]
-  val level1: ArrayList[ArrayList[String]] = ll.get(0)
-  val level2: ArrayList[String] = ll.get(0).get(0)
-  val level3: String = ll.get(0).get(0).get(0)
+  val level1: ArrayList[ArrayList[String]] = ll.get(0) // error
+  val level2: ArrayList[String] = ll.get(0).get(0) // error
+  val level3: String = ll.get(0).get(0).get(0)  // error
 
   val lb = new ArrayList[ArrayList[ArrayList[String]]]
   val levelA = lb.get(0)
-  val levelB = lb.get(0).get(0)
-  val levelC = lb.get(0).get(0).get(0)
+  val levelB = lb.get(0).get(0)  // error
+  val levelC = lb.get(0).get(0).get(0)  // error
 
-  val x = levelA.get(0)
+  val x = levelA.get(0)  // error
   val y = levelB.get(0)
-  val z: String = levelA.get(0).get(0)
+  val z: String = levelA.get(0).get(0)  // error
 }
diff --git a/tests/explicit-nulls/flexible-types/common/java-call/S.scala b/tests/explicit-nulls/flexible-types/common/java-call/S.scala
index 5c4b9c1ed8f7..e5f9abe70d5f 100644
--- a/tests/explicit-nulls/flexible-types/common/java-call/S.scala
+++ b/tests/explicit-nulls/flexible-types/common/java-call/S.scala
@@ -10,7 +10,7 @@ val s1n: String | Null = j.f1()
 
 val i1: Int = j.f2()
 
-val k: jj.K = jj.f3()
+val k: jj.K = jj.f3() // error // error
 
 val s2: String = j.g1[String]()  // error
 
diff --git a/tests/explicit-nulls/flexible-types/common/unsafe-match-null.scala b/tests/explicit-nulls/flexible-types/common/unsafe-match-null.scala
deleted file mode 100644
index 2055f51af5cd..000000000000
--- a/tests/explicit-nulls/flexible-types/common/unsafe-match-null.scala
+++ /dev/null
@@ -1,5 +0,0 @@
-def test1 =
-  val s: String = ???
-  s.trim() match
-    case _: String =>
-    case null => // error: Values of types Null and String cannot be compared
diff --git a/tests/explicit-nulls/flexible-types/common/equal/J.java b/tests/explicit-nulls/flexible-types/pos/equal/J.java
similarity index 100%
rename from tests/explicit-nulls/flexible-types/common/equal/J.java
rename to tests/explicit-nulls/flexible-types/pos/equal/J.java
diff --git a/tests/explicit-nulls/flexible-types/common/equal/S.scala b/tests/explicit-nulls/flexible-types/pos/equal/S.scala
similarity index 100%
rename from tests/explicit-nulls/flexible-types/common/equal/S.scala
rename to tests/explicit-nulls/flexible-types/pos/equal/S.scala
diff --git a/tests/flexible-types/pos/interop-constructor-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-constructor-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-constructor-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-constructor-src/J.java
diff --git a/tests/flexible-types/pos/interop-constructor-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-constructor-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-constructor-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-constructor-src/S.scala
diff --git a/tests/flexible-types/pos/interop-enum-src/Day.java b/tests/explicit-nulls/flexible-types/pos/interop-enum-src/Day.java
similarity index 100%
rename from tests/flexible-types/pos/interop-enum-src/Day.java
rename to tests/explicit-nulls/flexible-types/pos/interop-enum-src/Day.java
diff --git a/tests/flexible-types/pos/interop-enum-src/Planet.java b/tests/explicit-nulls/flexible-types/pos/interop-enum-src/Planet.java
similarity index 100%
rename from tests/flexible-types/pos/interop-enum-src/Planet.java
rename to tests/explicit-nulls/flexible-types/pos/interop-enum-src/Planet.java
diff --git a/tests/flexible-types/pos/interop-enum-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-enum-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-enum-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-enum-src/S.scala
diff --git a/tests/flexible-types/pos/interop-generics/J.java b/tests/explicit-nulls/flexible-types/pos/interop-generics/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-generics/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-generics/J.java
diff --git a/tests/flexible-types/pos/interop-generics/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-generics/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-generics/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-generics/S.scala
diff --git a/tests/flexible-types/pos/interop-match-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-match-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-match-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-match-src/J.java
diff --git a/tests/flexible-types/pos/interop-match-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-match-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-match-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-match-src/S.scala
diff --git a/tests/flexible-types/pos/interop-method-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-method-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-method-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-method-src/J.java
diff --git a/tests/flexible-types/pos/interop-method-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-method-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-method-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-method-src/S.scala
diff --git a/tests/flexible-types/pos/interop-ortype-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-ortype-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-ortype-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-ortype-src/J.java
diff --git a/tests/flexible-types/pos/interop-ortype-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-ortype-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-ortype-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-ortype-src/S.scala
diff --git a/tests/flexible-types/pos/interop-poly-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-poly-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-poly-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-poly-src/J.java
diff --git a/tests/flexible-types/pos/interop-poly-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-poly-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-poly-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-poly-src/S.scala
diff --git a/tests/flexible-types/pos/interop-sam-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-sam-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-sam-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-sam-src/J.java
diff --git a/tests/flexible-types/pos/interop-sam-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-sam-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-sam-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-sam-src/S.scala
diff --git a/tests/flexible-types/pos/interop-static-src/J.java b/tests/explicit-nulls/flexible-types/pos/interop-static-src/J.java
similarity index 100%
rename from tests/flexible-types/pos/interop-static-src/J.java
rename to tests/explicit-nulls/flexible-types/pos/interop-static-src/J.java
diff --git a/tests/flexible-types/pos/interop-static-src/S.scala b/tests/explicit-nulls/flexible-types/pos/interop-static-src/S.scala
similarity index 100%
rename from tests/flexible-types/pos/interop-static-src/S.scala
rename to tests/explicit-nulls/flexible-types/pos/interop-static-src/S.scala
diff --git a/tests/explicit-nulls/flexible-types/pos/match-null.scala b/tests/explicit-nulls/flexible-types/pos/match-null.scala
new file mode 100644
index 000000000000..4cdf7632fa35
--- /dev/null
+++ b/tests/explicit-nulls/flexible-types/pos/match-null.scala
@@ -0,0 +1,5 @@
+def test1 =
+  val s: String = ???
+  s.trim() match
+    case _: String =>
+    case null =>
diff --git a/tests/flexible-types/neg/array.scala b/tests/flexible-types/neg/array.scala
deleted file mode 100644
index 83e39cc80929..000000000000
--- a/tests/flexible-types/neg/array.scala
+++ /dev/null
@@ -1,44 +0,0 @@
-// Test array with nulls.
-
-class ArrayWithNulls {
-  def test1 = {
-    // A non-nullable array of non-nullable strings
-    val a1: Array[String] = Array("hello")
-    val s1: String = a1(0)
-    val s2: String | Null = a1(0)
-    val a2: Array[String] = Array()
-
-    // Array type is non-nullable
-    val b1: Array[String] = null // error
-    val b2: Array[Int] = null // error
-  }
-
-  def test2 = {
-    // A nullable array of non-nullable strings
-    val a1: Array[String] | Null = null
-    val a2: Array[String] | Null = Array()
-    val a3: Array[String] | Null = Array("")
-    val a4: Array[String] | Null = Array("", null) // error
-
-    // A non-nullable array of nullable strings
-    val b1: Array[String | Null] = Array()
-    val b2: Array[String | Null] = Array(null)
-    val b3: Array[String | Null] = Array("")
-    val b4: Array[String | Null] = Array("", null)
-    val b5: Array[String | Null] = null // error
-
-    val s1: String = b1(0) // error
-    val s2: String | Null = b1(0)
-
-    // A nullable array of nullable strings
-    val c1: Array[String | Null] | Null = Array()
-  }
-
-  def test3 = {
-    val a1: Array[String] = Array()
-
-    val a2: Array[String] | Null = a1
-
-    val a3: Array[String | Null] = a1 // error
-  }
-}
diff --git a/tests/flexible-types/pos-separate/interop-enum-src/Day_1.java b/tests/flexible-types/pos-separate/interop-enum-src/Day_1.java
deleted file mode 100644
index b5d96e446fa8..000000000000
--- a/tests/flexible-types/pos-separate/interop-enum-src/Day_1.java
+++ /dev/null
@@ -1,6 +0,0 @@
-
-public enum Day_1 {
-	SUN,
-	MON,
-	TUE
-}
diff --git a/tests/flexible-types/pos-separate/interop-enum-src/Planet_2.java b/tests/flexible-types/pos-separate/interop-enum-src/Planet_2.java
deleted file mode 100644
index c46e92d13bea..000000000000
--- a/tests/flexible-types/pos-separate/interop-enum-src/Planet_2.java
+++ /dev/null
@@ -1,19 +0,0 @@
-public enum Planet_2 {
-    MERCURY (3.303e+23, 2.4397e6),
-    VENUS   (4.869e+24, 6.0518e6),
-    EARTH   (5.976e+24, 6.37814e6),
-    MARS    (6.421e+23, 3.3972e6),
-    JUPITER (1.9e+27,   7.1492e7),
-    SATURN  (5.688e+26, 6.0268e7),
-    URANUS  (8.686e+25, 2.5559e7),
-    NEPTUNE (1.024e+26, 2.4746e7);
-
-    private final double mass;   // in kilograms
-    private final double radius; // in meters
-    Planet_2(double mass, double radius) {
-        this.mass = mass;
-        this.radius = radius;
-    }
-    private double mass() { return mass; }
-    private double radius() { return radius; }
-}
diff --git a/tests/flexible-types/pos-separate/interop-enum-src/S_3.scala b/tests/flexible-types/pos-separate/interop-enum-src/S_3.scala
deleted file mode 100644
index 3c5c8cd451ae..000000000000
--- a/tests/flexible-types/pos-separate/interop-enum-src/S_3.scala
+++ /dev/null
@@ -1,6 +0,0 @@
-
-// Verify that enum values aren't nullified.
-class S {
-  val d: Day_1 = Day_1.MON
-  val p: Planet_2 = Planet_2.MARS
-}
diff --git a/tests/flexible-types/pos/i8981.scala b/tests/flexible-types/pos/i8981.scala
deleted file mode 100644
index f72b508cf64e..000000000000
--- a/tests/flexible-types/pos/i8981.scala
+++ /dev/null
@@ -1 +0,0 @@
-class Foo extends javax.swing.JPanel
\ No newline at end of file
diff --git a/tests/flexible-types/pos/instanceof-nothing.scala b/tests/flexible-types/pos/instanceof-nothing.scala
deleted file mode 100644
index ef5fc4ede841..000000000000
--- a/tests/flexible-types/pos/instanceof-nothing.scala
+++ /dev/null
@@ -1,26 +0,0 @@
-// Check that calling `asInstanceOf[Nothing]` throws a ClassCastException.
-// In particular, the compiler needs access to the right method to throw
-// the exception, and identifying the method uses some explicit nulls related
-// logic (see ClassCastExceptionClass in Definitions.scala).
-
-object Test {
-  def main(args: Array[String]): Unit = {
-    val x: String = "hello"
-    try {
-      val y: Nothing = x.asInstanceOf[Nothing]
-      assert(false)
-    } catch {
-      case e: ClassCastException =>
-        // ok
-    }
-
-    val n: Null = null
-    try {
-      val y: Nothing = n.asInstanceOf[Nothing]
-      assert(false)
-    } catch {
-      case e: ClassCastException =>
-        // ok
-    }
-  }
-}
diff --git a/tests/flexible-types/pos/interop-array-src/J.java b/tests/flexible-types/pos/interop-array-src/J.java
deleted file mode 100644
index 741c3739b296..000000000000
--- a/tests/flexible-types/pos/interop-array-src/J.java
+++ /dev/null
@@ -1,13 +0,0 @@
-class J {
-	void foo1(String[] ss) {}
-
-	String[] foo2() {
-		return new String[]{""};
-	}
-
-	void bar1(int[] is) {}
-
-	int[] bar2() {
-		return new int[]{0};
-	}
-}
diff --git a/tests/flexible-types/pos/interop-array-src/S.scala b/tests/flexible-types/pos/interop-array-src/S.scala
deleted file mode 100644
index 6741ad50e351..000000000000
--- a/tests/flexible-types/pos/interop-array-src/S.scala
+++ /dev/null
@@ -1,25 +0,0 @@
-class S {
-
-  val j = new J()
-
-  def f =  {
-    val x1: Array[String|Null]|Null = ???
-    j.foo1(x1) // error: expected Array[String | Null] but got Array[String]
-
-    val x2: Array[String | Null] = ???
-    j.foo1(x2) // ok
-    j.foo1(null) // ok
-
-    val y1: Array[String] = j.foo2() // error
-    val y2: Array[String | Null] = j.foo2() // error: expected Array[String | Null] but got Array[String]
-    val y3: Array[String | Null] | Null = j.foo2()
-  }
-
-  def g =  {
-    val x1: Array[Int] = ???
-    j.bar1(x1) // ok
-
-    val y1: Array[Int] = j.bar2() // error
-    val y2: Array[Int] | Null = j.bar2()
-  }
-}
diff --git a/tests/flexible-types/pos/interop-compare-src/J.java b/tests/flexible-types/pos/interop-compare-src/J.java
deleted file mode 100644
index fcd07e47764c..000000000000
--- a/tests/flexible-types/pos/interop-compare-src/J.java
+++ /dev/null
@@ -1,5 +0,0 @@
-class J {
-  public String foo(String s) {
-      return s;
-  }
-}
diff --git a/tests/flexible-types/pos/interop-compare-src/S.scala b/tests/flexible-types/pos/interop-compare-src/S.scala
deleted file mode 100644
index 3624a92180c6..000000000000
--- a/tests/flexible-types/pos/interop-compare-src/S.scala
+++ /dev/null
@@ -1,10 +0,0 @@
-@main def main() = {
-  val j: J = new J
-  if (j.foo(null) == null) {
-    println("null")
-  }
-  val x = j.foo("a")
-  if (x == null) {
-    println("null")
-  }
-}
diff --git a/tests/flexible-types/pos/interop-constructor.scala b/tests/flexible-types/pos/interop-constructor.scala
deleted file mode 100644
index 4ebfaa752b3a..000000000000
--- a/tests/flexible-types/pos/interop-constructor.scala
+++ /dev/null
@@ -1,7 +0,0 @@
-// Test that constructors have a non-nullable return type.
-
-class Foo {
-  val x: java.lang.String = new java.lang.String()
-  val y: java.util.Date = new java.util.Date()
-  val v = new java.util.Vector[String](null /*stands for Collection<? extends E>*/)
-}
diff --git a/tests/flexible-types/pos/interop-java-varargs-src/Names.java b/tests/flexible-types/pos/interop-java-varargs-src/Names.java
deleted file mode 100644
index e46b406749ce..000000000000
--- a/tests/flexible-types/pos/interop-java-varargs-src/Names.java
+++ /dev/null
@@ -1,4 +0,0 @@
-
-class Names {
-  static void setNames(String... names) {}
-}
diff --git a/tests/flexible-types/pos/interop-java-varargs-src/S.scala b/tests/flexible-types/pos/interop-java-varargs-src/S.scala
deleted file mode 100644
index e867202e506d..000000000000
--- a/tests/flexible-types/pos/interop-java-varargs-src/S.scala
+++ /dev/null
@@ -1,19 +0,0 @@
-// Test that nullification can handle Java varargs.
-// For varargs, the element type is nullified, but the top level argument isn't.
-
-class S {
-  // Pass an empty array.
-  Names.setNames()
-
-  // Pass a singleton array with null as an element.
-  Names.setNames(null)
-
-  // Pass a singleton array.
-  Names.setNames("name1")
-
-  // Multiple arguments.
-  Names.setNames("name1", "name2", "name3", "name4")
-
-  // Multiple arguments, some null.
-  Names.setNames(null, null, "hello", "world", null)
-}
diff --git a/tests/flexible-types/pos/interop-java-varargs.scala b/tests/flexible-types/pos/interop-java-varargs.scala
deleted file mode 100644
index 46dc388d02af..000000000000
--- a/tests/flexible-types/pos/interop-java-varargs.scala
+++ /dev/null
@@ -1,22 +0,0 @@
-import java.nio.file.*
-import java.nio.file.Paths
-
-class S {
-
-  // Paths.get is a Java method with two arguments, where the second one
-  // is a varargs: https://docs.oracle.com/javase/8/docs/api/java/nio/file/Paths.html
-  // static Path get(String first, String... more)
-  // The Scala compiler converts this signature into
-  // def get(first: String | Null, more: (String | Null)*)
-
-  // Test that we can avoid providing the varargs argument altogether.
-  Paths.get("out")
-
-  // Test with one argument in the varargs.
-  Paths.get("home", "src")
-  Paths.get("home", null)
-
-  // Test multiple arguments in the varargs.
-  Paths.get("home", "src", "compiler", "src")
-  Paths.get("home", null, null, null)
-}
diff --git a/tests/flexible-types/pos/override-java-object-arg-src/J.java b/tests/flexible-types/pos/override-java-object-arg-src/J.java
deleted file mode 100644
index efcb630b7b6c..000000000000
--- a/tests/flexible-types/pos/override-java-object-arg-src/J.java
+++ /dev/null
@@ -1,10 +0,0 @@
-
-// Copy of https://docs.oracle.com/javase/7/docs/api/javax/management/NotificationListener.html
-
-class Notification {};
-
-interface NotificationListener {
-
-  void handleNotification(Notification notification, Object handback);   
-
-}
diff --git a/tests/flexible-types/pos/override-java-object-arg-src/S.scala b/tests/flexible-types/pos/override-java-object-arg-src/S.scala
deleted file mode 100644
index 757a3b6b1235..000000000000
--- a/tests/flexible-types/pos/override-java-object-arg-src/S.scala
+++ /dev/null
@@ -1,33 +0,0 @@
-// This test is like tests/pos/override-java-object-arg.scala, except that
-// here we load the Java code from source, as opposed to a class file.
-// In this case, the Java 'Object' type is turned into 'AnyRef', not 'Any'.
-
-class S {
-
-  def bar(): Unit = {
-    val listener = new NotificationListener() {
-      override def handleNotification(n: Notification|Null, emitter: Object|Null): Unit = {
-      }
-    }
-
-    val listener2 = new NotificationListener() {
-      override def handleNotification(n: Notification|Null, emitter: AnyRef|Null): Unit = {
-      }
-    }
-
-    val listener3 = new NotificationListener() {
-      override def handleNotification(n: Notification|Null, emitter: Object): Unit = {
-      }
-    }
-
-    val listener4 = new NotificationListener() {
-      override def handleNotification(n: Notification, emitter: Object|Null): Unit = {
-      }
-    }
-
-    val listener5 = new NotificationListener() {
-      override def handleNotification(n: Notification, emitter: Object): Unit = {
-      }
-    }
-  }
-}
diff --git a/tests/flexible-types/pos/override-java-object-arg.scala b/tests/flexible-types/pos/override-java-object-arg.scala
deleted file mode 100644
index 8c5a76e15a6c..000000000000
--- a/tests/flexible-types/pos/override-java-object-arg.scala
+++ /dev/null
@@ -1,43 +0,0 @@
-// When we load a Java class file, if a java method has an argument with type
-// 'Object', it (the method argument) gets loaded by Dotty as 'Any' (as opposed to 'AnyRef').
-// This is pre-explicit-nulls behaviour.
-// There is special logic in the type comparer that allows that method to be overridden
-// with a corresponding argument with type 'AnyRef | Null' (or `Object | Null`).
-// This test verifies that we can continue to override such methods, except that in
-// the explicit nulls world we override with 'AnyRef|Null'.
-
-import javax.management.{Notification, NotificationEmitter, NotificationListener}
-
-class Foo {
-
-  def bar(): Unit = {
-    val listener = new NotificationListener() {
-      // The second argument in the base interface is loaded with type 'Any', but we override
-      // it with 'AnyRef|Null'.
-      override def handleNotification(n: Notification|Null, emitter: Object|Null): Unit = {
-      }
-    }
-
-    val listener2 = new NotificationListener() {
-      // The second argument in the base interface is loaded with type 'Any', but we override
-      // it with 'AnyRef|Null'.
-      override def handleNotification(n: Notification|Null, emitter: AnyRef|Null): Unit = {
-      }
-    }
-
-    val listener3 = new NotificationListener() {
-      override def handleNotification(n: Notification|Null, emitter: Object): Unit = {
-      }
-    }
-
-    val listener4 = new NotificationListener() {
-      override def handleNotification(n: Notification, emitter: Object|Null): Unit = {
-      }
-    }
-
-    val listener5 = new NotificationListener() {
-      override def handleNotification(n: Notification, emitter: Object): Unit = {
-      }
-    }
-  }
-}
diff --git a/tests/flexible-types/pos/override-java-varargs/S.scala b/tests/flexible-types/pos/override-java-varargs/S.scala
deleted file mode 100644
index bb98c86b455c..000000000000
--- a/tests/flexible-types/pos/override-java-varargs/S.scala
+++ /dev/null
@@ -1,14 +0,0 @@
-class S1 extends J {
-  override def foo(x: (String | Null)*): Unit = ???
-  override def bar(x: String | Null, y: (String | Null)*): Unit = ???
-}
-
-class S2 extends J {
-  override def foo(x: String*): Unit = ???
-  override def bar(x: String | Null, y: String*): Unit = ???
-}
-
-class S3 extends J {
-  override def foo(x: String*): Unit = ???
-  override def bar(x: String, y: String*): Unit = ???
-}
diff --git a/tests/flexible-types/pos/override-java/J1.java b/tests/flexible-types/pos/override-java/J1.java
deleted file mode 100644
index 0c66c26fdea9..000000000000
--- a/tests/flexible-types/pos/override-java/J1.java
+++ /dev/null
@@ -1,4 +0,0 @@
-abstract class J1 {
-  abstract void foo1(String x);
-  abstract String foo2();
-}
\ No newline at end of file
diff --git a/tests/flexible-types/pos/override-java/J2.java b/tests/flexible-types/pos/override-java/J2.java
deleted file mode 100644
index 8ff04d59f54f..000000000000
--- a/tests/flexible-types/pos/override-java/J2.java
+++ /dev/null
@@ -1,9 +0,0 @@
-import java.util.List;
-
-abstract class J2 {
-  abstract void bar1(List<String> xs);
-  abstract void bar2(List<String[]> xss);
-
-  abstract List<String> bar3();
-  abstract List<String[]> bar4();
-}
\ No newline at end of file
diff --git a/tests/flexible-types/pos/override-java/S1.scala b/tests/flexible-types/pos/override-java/S1.scala
deleted file mode 100644
index 01a95c8e0ef7..000000000000
--- a/tests/flexible-types/pos/override-java/S1.scala
+++ /dev/null
@@ -1,9 +0,0 @@
-class S1a extends J1 {
-  override def foo1(x: String | Null): Unit = ???
-  override def foo2(): String | Null = ???
-}
-
-class S1b extends J1 {
-  override def foo1(x: String): Unit = ???
-  override def foo2(): String = ???
-}
\ No newline at end of file
diff --git a/tests/flexible-types/pos/override-java/S2.scala b/tests/flexible-types/pos/override-java/S2.scala
deleted file mode 100644
index ec440ca8f150..000000000000
--- a/tests/flexible-types/pos/override-java/S2.scala
+++ /dev/null
@@ -1,25 +0,0 @@
-import java.util.List
-
-class S2a extends J2 {
-  override def bar1(xs: List[String] | Null): Unit = ???
-  override def bar2(xss: List[Array[String | Null]] | Null): Unit = ???
-
-  override def bar3(): List[String] | Null = ???
-  override def bar4(): List[Array[String | Null]] | Null = ???
-}
-
-class S2b extends J2 {
-  override def bar1(xs: List[String]): Unit = ???
-  override def bar2(xss: List[Array[String | Null]]): Unit = ???
-
-  override def bar3(): List[String] = ???
-  override def bar4(): List[Array[String | Null]] = ???
-}
-
-class S2c extends J2 {
-  override def bar1(xs: List[String]): Unit = ???
-  override def bar2(xss: List[Array[String]]): Unit = ???
-
-  override def bar3(): List[String] = ???
-  override def bar4(): List[Array[String]] = ???
-}
\ No newline at end of file
diff --git a/tests/flexible-types/pos/override-type-params.scala b/tests/flexible-types/pos/override-type-params.scala
deleted file mode 100644
index 7f59409a4c3c..000000000000
--- a/tests/flexible-types/pos/override-type-params.scala
+++ /dev/null
@@ -1,18 +0,0 @@
-// Testing relaxed overriding check for explicit nulls.
-// The relaxed check is only enabled if one of the members is Java defined.
-
-import java.util.Comparator
-
-class C1[T <: AnyRef] extends Ordering[T]:
-  override def compare(o1: T, o2: T): Int = 0
-
-// The following overriding is not allowed, because `compare`
-// has already been declared in Scala class `Ordering`.
-// class C2[T <: AnyRef] extends Ordering[T]:
-//   override def compare(o1: T | Null, o2: T | Null): Int = 0
-
-class D1[T <: AnyRef] extends Comparator[T]:
-  override def compare(o1: T, o2: T): Int = 0
-
-class D2[T <: AnyRef] extends Comparator[T]:
-  override def compare(o1: T | Null, o2: T | Null): Int = 0
diff --git a/tests/flexible-types/run/array/J.java b/tests/flexible-types/run/array/J.java
deleted file mode 100644
index 6fb5d625b872..000000000000
--- a/tests/flexible-types/run/array/J.java
+++ /dev/null
@@ -1,4 +0,0 @@
-public class J {
-    public J(java.lang.String s) {
-    }
-}
diff --git a/tests/flexible-types/run/array/Test.scala b/tests/flexible-types/run/array/Test.scala
deleted file mode 100644
index b37329cacbce..000000000000
--- a/tests/flexible-types/run/array/Test.scala
+++ /dev/null
@@ -1,31 +0,0 @@
-/*
-class Foo {
-  def err(msg: String): Nothing = {
-    throw new RuntimeException("Hello")
-  }
-  def retTypeNothing(): String = {
-    val y: String|Null = ???
-    if (y == null) err("y is null!")
-    y
-  }
-}
-*/
-
-
-object Test {
-  def main(args: Array[String]): Unit = {
-    val i : Integer = new Integer(3) // Constructor with non-ref arg
-    val s1 : String | Null = new String("abc") // Constructor with ref arg
-    val s2 : String = new String("abc") // Constructor with ref arg, not null
-    val s3 = s1.nn.substring(0,1).substring(0,1)
-    val s4 = s2.substring(0,1).substring(0,1)
-    val s5 = s4.startsWith(s4)
-    // s1.substring(0,1) // error
-    val j : J = new J("")
-    println(s4)
-    //val f : Foo = new Foo("x")
-    //f.err("Hello")
-    //val l : List[String] = Java.returnsNull();
-    //val j : J = new J
-  }
-}
diff --git a/tests/flexible-types/run/erasure.scala b/tests/flexible-types/run/erasure.scala
deleted file mode 100644
index 1f43bde49a2e..000000000000
--- a/tests/flexible-types/run/erasure.scala
+++ /dev/null
@@ -1,8 +0,0 @@
-object Test {
-  def main(args: Array[String]): Unit = {
-    val v: Vector[String | Null] = Vector("a", "b")
-    val v2: Vector[String] = Vector("a", "b")
-    println(v)
-    println(v2)
-  }
-}
diff --git a/tests/flexible-types/run/generic-java-array-src/JA.java b/tests/flexible-types/run/generic-java-array-src/JA.java
deleted file mode 100644
index ccca309d4f49..000000000000
--- a/tests/flexible-types/run/generic-java-array-src/JA.java
+++ /dev/null
@@ -1,13 +0,0 @@
-class JA {
-  public static <T> T get(T[] arr) {
-    return arr[0];
-  }
-
-  public static int getInt(int[] arr) {
-    return arr[0];	  
-  }
-
-  public static boolean getBool(boolean[] arr) {
-    return arr[0];	   
-  }
-}
diff --git a/tests/flexible-types/run/generic-java-array-src/Test.scala b/tests/flexible-types/run/generic-java-array-src/Test.scala
deleted file mode 100644
index 26e4886d499b..000000000000
--- a/tests/flexible-types/run/generic-java-array-src/Test.scala
+++ /dev/null
@@ -1,21 +0,0 @@
-object Test {
-  def main(args: Array[String]): Unit = {
-    // This test shows that if we have a Java method that takes a generic array,
-    // then on the Scala side we'll need to pass a nullable array.
-    // i.e. with explicit nulls the previously-implicit cast becomes an explicit
-    // type annotation.
-    val x = new Array[Integer|Null](1)
-    x(0) = 10
-    println(JA.get(x))
-
-    // However, if the Java method takes an array that's explicitly of a value type,
-    // then we can pass a non-nullable array from the Scala side.
-    val intArr = new Array[Int](1)
-    intArr(0) = 20
-    println(JA.getInt(intArr))
-
-    val boolArr = new Array[Boolean](1)
-    boolArr(0) = true
-    println(JA.getBool(boolArr))
-  }
-}
diff --git a/tests/flexible-types/run/i11332.scala b/tests/flexible-types/run/i11332.scala
deleted file mode 100644
index 73fb48839c16..000000000000
--- a/tests/flexible-types/run/i11332.scala
+++ /dev/null
@@ -1,22 +0,0 @@
-// scalajs: --skip
-import scala.language.unsafeNulls
-
-import java.lang.invoke._, MethodType.methodType
-
-// A copy of tests/run/i11332.scala
-// to test the bootstrap minimisation which failed
-// (because bootstrap runs under explicit nulls)
-class Foo:
-  def neg(x: Int): Int = -x
-
-object Test:
-  def main(args: Array[String]): Unit =
-    val l    = MethodHandles.lookup()
-    val self = new Foo()
-
-    val res4 = {
-      l // explicit chain method call - previously derivedSelect broke the type
-        .findVirtual(classOf[Foo], "neg", methodType(classOf[Int], classOf[Int]))
-        .invokeExact(self, 4): Int
-    }
-    assert(-4 == res4)
diff --git a/tests/flexible-types/run/instanceof-nothing.scala b/tests/flexible-types/run/instanceof-nothing.scala
deleted file mode 100644
index ef5fc4ede841..000000000000
--- a/tests/flexible-types/run/instanceof-nothing.scala
+++ /dev/null
@@ -1,26 +0,0 @@
-// Check that calling `asInstanceOf[Nothing]` throws a ClassCastException.
-// In particular, the compiler needs access to the right method to throw
-// the exception, and identifying the method uses some explicit nulls related
-// logic (see ClassCastExceptionClass in Definitions.scala).
-
-object Test {
-  def main(args: Array[String]): Unit = {
-    val x: String = "hello"
-    try {
-      val y: Nothing = x.asInstanceOf[Nothing]
-      assert(false)
-    } catch {
-      case e: ClassCastException =>
-        // ok
-    }
-
-    val n: Null = null
-    try {
-      val y: Nothing = n.asInstanceOf[Nothing]
-      assert(false)
-    } catch {
-      case e: ClassCastException =>
-        // ok
-    }
-  }
-}
diff --git a/tests/flexible-types/run/interop-unsound-src/J.java b/tests/flexible-types/run/interop-unsound-src/J.java
deleted file mode 100644
index e06b22c3bae2..000000000000
--- a/tests/flexible-types/run/interop-unsound-src/J.java
+++ /dev/null
@@ -1,17 +0,0 @@
-
-class JavaBox<T> {
-	T contents;
-
-	JavaBox(T contents) { this.contents = contents; }
-}
-
-class Forwarder {
-
-  static <T extends JavaBox<String>> void putInJavaBox(T box, String s) {
-	box.contents = s;
-  }
-  
-  static <T extends ScalaBox<String>> void putInScalaBox(T box, String s) {
-	box.setContents(s);  
-  }
-}
diff --git a/tests/flexible-types/run/interop-unsound-src/S.scala b/tests/flexible-types/run/interop-unsound-src/S.scala
deleted file mode 100644
index 2e5eca0c1e5b..000000000000
--- a/tests/flexible-types/run/interop-unsound-src/S.scala
+++ /dev/null
@@ -1,33 +0,0 @@
-// An example that shows that the nullability transform is unsound.
-
-class ScalaBox[T](init: T) {
-  var contents: T = init
-
-  def setContents(c: T): Unit = {
-    contents = c
-  }
-}
-
-object Test {
-
-  def main(args: Array[String]): Unit = {
-    val jb: JavaBox[String] = new JavaBox("hello")
-    val sb: ScalaBox[String] = ScalaBox("world")
-
-    Forwarder.putInJavaBox(jb, null) // not unsound, becase JavaBox is java-defined
-                                     // so the contents fields will have a nullable
-                                     // type
-    
-    Forwarder.putInScalaBox(sb, null) // this is unsound, because ScalaBox
-                                      // should contain only Strings, but we added
-                                      // a null
-    
-    try {
-      sb.contents.length
-      assert(false)
-    } catch {
-      case ex: NullPointerException =>
-        // expected
-    }
-  }
-}