Back-port fix for ModuleDescriptor.hashCode()

* 8275509: ModuleDescriptor.hashCode isn't reproducible across builds
* 8290041: ModuleDescriptor.hashCode is inconsistent

Signed-off-by: Keith W. Campbell <[email protected]>

Author: keithc-ca

src/java.base/share/classes/java/lang/module/ModuleDescriptor.java

@@ -327,7 +327,7 @@ public boolean equals(Object ob) {
          */
         @Override
         public int hashCode() {
-            int hash = name.hashCode() * 43 + mods.hashCode();
+            int hash = name.hashCode() * 43 + modsHashCode(mods);
             if (compiledVersion != null)
                 hash = hash * 43 + compiledVersion.hashCode();
             if (rawCompiledVersion != null)
@@ -505,7 +505,7 @@ public int compareTo(Exports that) {
          */
         @Override
         public int hashCode() {
-            int hash = mods.hashCode();
+            int hash = modsHashCode(mods);
             hash = hash * 43 + source.hashCode();
             return hash * 43 + targets.hashCode();
         }
@@ -708,7 +708,7 @@ public int compareTo(Opens that) {
          */
         @Override
         public int hashCode() {
-            int hash = mods.hashCode();
+            int hash = modsHashCode(mods);
             hash = hash * 43 + source.hashCode();
             return hash * 43 + targets.hashCode();
         }
@@ -2261,7 +2261,7 @@ public int hashCode() {
         int hc = hash;
         if (hc == 0) {
             hc = name.hashCode();
-            hc = hc * 43 + Objects.hashCode(modifiers);
+            hc = hc * 43 + modsHashCode(modifiers);
             hc = hc * 43 + requires.hashCode();
             hc = hc * 43 + Objects.hashCode(packages);
             hc = hc * 43 + exports.hashCode();
@@ -2546,6 +2546,18 @@ private static <M> String toString(Set<M> mods, String what) {
                 .collect(Collectors.joining(" "));
     }
 
+    /**
+     * Generates and returns a hashcode for the enum instances. The returned hashcode
+     * is a value based on the {@link Enum#name() name} of each enum instance.
+     */
+    private static int modsHashCode(Iterable<? extends Enum<?>> enums) {
+        int h = 0;
+        for (Enum<?> e : enums) {
+            h += e.name().hashCode();
+        }
+        return h;
+    }
+
     private static <T extends Object & Comparable<? super T>>
     int compare(T obj1, T obj2) {
         if (obj1 != null) {