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 <keithc@ca.ibm.com>

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

@@ -333,7 +333,7 @@ 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)
@@ -514,7 +514,7 @@ 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();
  }
@@ -721,7 +721,7 @@ 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();
  }
@@ -2283,7 +2283,7 @@ 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();
@@ -2568,6 +2568,18 @@ 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) {