Fix the update validation error while stopping an idling workspace.

infrastructures/kubernetes/src/main/java/org/eclipse/che/workspace/infrastructure/kubernetes/K8sInfraNamespaceWsAttributeValidator.java

@@ -109,6 +109,17 @@ public void validateUpdate(Map<String, String> existing, Map<String, String> upd
               WORKSPACE_INFRASTRUCTURE_NAMESPACE_ATTRIBUTE, existingNamespace));
     }
 
+    if (isNullOrEmpty(existingNamespace)) {
+      // this would mean that the user made an update to the workspace without it having the
+      // namespace attribute stored. This is very, very unlikely, because the setting of attributes
+      // happens during the creation process. But let's just cover this case anyway, just to be
+      // sure.
+      validate(update);
+
+      // everything is fine. We allow to change infra namespace in such case.
+      return;
+    }
+
     if (!updateNamespace.equals(existingNamespace)) {
       throw new ValidationException(
           format(

infrastructures/kubernetes/src/test/java/org/eclipse/che/workspace/infrastructure/kubernetes/K8sInfraNamespaceWsAttributeValidatorTest.java

@@ -13,9 +13,13 @@
 
 import static java.util.Collections.emptyMap;
 import static org.eclipse.che.api.workspace.shared.Constants.WORKSPACE_INFRASTRUCTURE_NAMESPACE_ATTRIBUTE;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.doThrow;
 import static org.mockito.Mockito.lenient;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyZeroInteractions;
 
 import com.google.common.collect.ImmutableMap;
@@ -112,6 +116,24 @@ public void shouldDoNotAllowToRemoveNamespaceAttribute() throws ValidationExcept
         emptyMap());
   }
 
+  @Test
+  public void shouldValidateFullyIfExistingIsEmpty() throws ValidationException {
+    validator.validateUpdate(
+        emptyMap(),
+        ImmutableMap.of(WORKSPACE_INFRASTRUCTURE_NAMESPACE_ATTRIBUTE, "che-workspaces"));
+
+    verify(namespaceFactory).checkIfNamespaceIsAllowed(eq("che-workspaces"));
+  }
+
+  @Test
+  public void shouldNotValidateFullyIfExistingIsNotEmpty() throws ValidationException {
+    validator.validateUpdate(
+        ImmutableMap.of(WORKSPACE_INFRASTRUCTURE_NAMESPACE_ATTRIBUTE, "che-workspaces"),
+        ImmutableMap.of(WORKSPACE_INFRASTRUCTURE_NAMESPACE_ATTRIBUTE, "che-workspaces"));
+
+    verify(namespaceFactory, never()).checkIfNamespaceIsAllowed(any());
+  }
+
   @DataProvider
   public Object[][] invalidNamespaces() {
     return new String[][] {{"name!space"}, {"name@space"}, {"-namespace"}, {"namespace-"}};

wsmaster/che-core-api-workspace/src/main/java/org/eclipse/che/api/workspace/server/WorkspaceAttributeValidator.java

@@ -36,6 +36,9 @@ public interface WorkspaceAttributeValidator {
   /**
    * Validates if the specified workspace attributes can be updated with new values.
    *
+   * <p>Note that this method must not allow updates that would not validate using the {@link
+   * #validate(Map)} method.
+   *
    * <p>This check includes:
    *
    * <ul>

wsmaster/che-core-api-workspace/src/main/java/org/eclipse/che/api/workspace/server/WorkspaceValidator.java

@@ -123,17 +123,14 @@ public void validateAttributes(Map<String, String> attributes) throws Validation
   }
 
   /**
-   * Checks whether workspace attributes are valid on updating. The attribute is valid if it's key
-   * is not null & not empty & is not prefixed with 'codenvy'.
+   * Checks whether workspace attributes are valid on updating.
    *
    * @param existing actual attributes
    * @param update new attributes that are going to be stored instead of existing
    * @throws ValidationException when attributes are not valid
    */
   public void validateUpdateAttributes(Map<String, String> existing, Map<String, String> update)
       throws ValidationException {
-    validateAttributes(update);
-
     for (WorkspaceAttributeValidator attributeValidator : attributeValidators) {
       attributeValidator.validateUpdate(existing, update);
     }