Fix jarinfer cli output determinism (#884)

When invoking CLI, jar output sha is not constant. This breaks
cacheability in build systems like Buck and Bazel.
Binary investigation (see attached screenshot) of these jars show byte
0xa-0xd in PkZip header is what is changes, and corresponds to file
modified date/time (see
https://users.cs.jmu.edu/buchhofp/forensics/formats/pkzip.html).
This PR is setting these times to 0 explicilty, so that jar sha remains
constant between invocation.


---------

Co-authored-by: Manu Sridharan <msridhar@gmail.com>

jar-infer/jar-infer-lib/src/main/java/com/uber/nullaway/jarinfer/BytecodeAnnotator.java

@@ -212,6 +212,18 @@ public static void annotateBytecodeInClass(
     annotateBytecode(is, os, nonnullParams, nullableReturns, javaxNullableDesc, javaxNonnullDesc);
   }
 
+  /**
+   * Create a zip entry with creation time of 0 to ensure that jars always have the same checksum.
+   *
+   * @param name of the zip entry.
+   * @return the zip entry.
+   */
+  private static ZipEntry createZipEntry(String name) {
+    ZipEntry entry = new ZipEntry(name);
+    entry.setTime(0);
+    return entry;
+  }
+
   private static void copyAndAnnotateJarEntry(
       JarEntry jarEntry,
       InputStream is,
@@ -224,7 +236,7 @@ private static void copyAndAnnotateJarEntry(
       throws IOException {
     String entryName = jarEntry.getName();
     if (entryName.endsWith(".class")) {
-      jarOS.putNextEntry(new ZipEntry(jarEntry.getName()));
+      jarOS.putNextEntry(createZipEntry(jarEntry.getName()));
       annotateBytecode(is, jarOS, nonnullParams, nullableReturns, nullableDesc, nonnullDesc);
     } else if (entryName.equals("META-INF/MANIFEST.MF")) {
       // Read full file
@@ -241,7 +253,7 @@ private static void copyAndAnnotateJarEntry(
       if (!manifestText.equals(manifestMinusDigests) && !stripJarSignatures) {
         throw new SignedJarException(SIGNED_JAR_ERROR_MESSAGE);
       }
-      jarOS.putNextEntry(new ZipEntry(jarEntry.getName()));
+      jarOS.putNextEntry(createZipEntry(jarEntry.getName()));
       jarOS.write(manifestMinusDigests.getBytes(UTF_8));
     } else if (entryName.startsWith("META-INF/")
         && (entryName.endsWith(".DSA")
@@ -251,7 +263,7 @@ private static void copyAndAnnotateJarEntry(
         throw new SignedJarException(SIGNED_JAR_ERROR_MESSAGE);
       } // the case where stripJarSignatures==true is handled by default by skipping these files
     } else {
-      jarOS.putNextEntry(new ZipEntry(jarEntry.getName()));
+      jarOS.putNextEntry(createZipEntry(jarEntry.getName()));
       jarOS.write(IOUtils.toByteArray(is));
     }
     jarOS.closeEntry();
@@ -329,7 +341,7 @@ public static void annotateBytecodeInAar(
     while (zipIterator.hasNext()) {
       ZipEntry zipEntry = zipIterator.next();
       InputStream is = inputZip.getInputStream(zipEntry);
-      zipOS.putNextEntry(new ZipEntry(zipEntry.getName()));
+      zipOS.putNextEntry(createZipEntry(zipEntry.getName()));
       if (zipEntry.getName().equals("classes.jar")) {
         JarInputStream jarIS = new JarInputStream(is);
         JarEntry inputJarEntry = jarIS.getNextJarEntry();