Kotlin: hide from Java what can be hidden for enumerations (#1799)

---------- Motivation ----------
The elements with 'internal' Kotlin visibility become 'public'
when they are accessed from Java. Because of that internal
enumerations become fully visible in Java.

The 'JvmSynthetic' can be used on the aliasing enumerators
and on the value field of enumeration to hide as much as we can.

---------- Solution ----------
This commit:
 1. Implements 'JvmSynthetic' handling in mustache templates for enumerations.
 2. Adjusts smoke tests to showcase that 'JvmSynthetic' is generated.
 3. Removes Kotlin-Java interoperability test to show, that mentioned elements cannot be access by Java.

Signed-off-by: Patryk Wrobel <183546751+pwrobeldev@users.noreply.github.com>

Author: pwrobeldev

functional-tests/functional/android/src/test/java/com/here/android/test/VisibilityAttributeTest.java

@@ -103,17 +103,9 @@ public void internalFieldCtorCanBeCalled() {
   @Test
   public void valueOfInternalEnumCanBeAccessed() {
     SomeInternalEnum someObject = SomeInternalEnum.TWO;
-    assertEquals(2, someObject.value);
     assertEquals(SomeInternalEnum.TWO, someObject);
   }
 
-  @Test
-  public void internalAliasOfEnumCanBeAccessed() {
-    SomeInternalEnum someObject = SomeInternalEnum.SINGLE;
-    assertEquals(1, someObject.value);
-    assertEquals(SomeInternalEnum.ONE, someObject);
-  }
-
   @Test
   public void internaInterfaceFromJavaCanBeUsed() {
     ImplementationOfSomeInternalInterface someInterfaceImpl = new ImplementationOfSomeInternalInterface();

gluecodium/src/main/resources/templates/kotlin/KotlinEnumeration.mustache

@@ -24,7 +24,11 @@
 {{/unless}}{{/internalApiAnnotation}}internal {{!!
 }}{{/if}}{{!!
 }}{{#unless external.kotlin.converter}}{{>kotlin/KotlinTypeVisibility}}{{/unless}}{{!!
-}}enum class {{resolveName}}(@JvmField {{resolveName "visibility"}}val value: Int) {
+}}enum class {{resolveName}}(@JvmField {{!!
+}}{{#resolveName "visibility"}}{{!!
+}}{{#unless this.isEmpty}}@JvmSynthetic {{/unless}}{{!!
+}}{{this}}{{!!
+}}{{/resolveName}}val value: Int) {
 {{joinPartial uniqueEnumerators "kotlin/KotlinEnumerator" ",
 "}}{{#if uniqueEnumerators}};{{/if}}{{#if aliasEnumerators}}
 

gluecodium/src/main/resources/templates/kotlin/KotlinEnumerator.mustache

@@ -21,6 +21,10 @@
 {{#if comment}}
 {{prefixPartial "kotlin/KotlinDocComment" "    "}}{{/if}}{{!!
 }}{{prefixPartial "kotlin/KotlinAttributes" "    "}}{{!!
-}}{{#if isAlias}}    @JvmField {{resolveName "visibility"}}val {{resolveName}}{{!!
+}}{{#if isAlias}}    @JvmField {{!!
+}}{{#resolveName "visibility"}}{{!!
+}}{{#unless this.isEmpty}}@JvmSynthetic {{/unless}}{{!!
+}}{{this}}{{!!
+}}{{/resolveName}}val {{resolveName}}{{!!
 }} = {{resolveName value}}{{/if}}{{!!
 }}{{#unless isAlias}}    {{resolveName}}({{resolveName value}}){{/unless}}

gluecodium/src/test/resources/smoke/annotations/output/android-kotlin/com/example/smoke/OuterInternalEnum.kt

@@ -11,7 +11,7 @@ package com.example.smoke
 import com.example.MySmokeTestsInternalApi
 
 @MySmokeTestsInternalApi
-internal enum class OuterInternalEnum(@JvmField internal val value: Int) {
+internal enum class OuterInternalEnum(@JvmField @JvmSynthetic internal val value: Int) {
     FIRST(1),
     SECOND(2);
 }

gluecodium/src/test/resources/smoke/errors/output/android-kotlin/com/example/smoke/SomeInternalEnum.kt

@@ -5,16 +5,17 @@
 
 @file:JvmName("SomeInternalEnumExtensions")
 
+
 package com.example.smoke
 
 
-internal enum class SomeInternalEnum(@JvmField internal val value: Int) {
+internal enum class SomeInternalEnum(@JvmField @JvmSynthetic internal val value: Int) {
     ONE(1),
     TWO(2),
     THREE(3);
 
     companion object {
-        @JvmField internal val SINGLE = SomeInternalEnum.ONE
+        @JvmField @JvmSynthetic internal val SINGLE = SomeInternalEnum.ONE
     }
 
 }

gluecodium/src/test/resources/smoke/visibility_attribute/output/android-kotlin/com/example/smoke/PublicClass.kt

@@ -5,13 +5,14 @@
 
 @file:JvmName("PublicClassExtensions")
 
+
 package com.example.smoke
 
 import com.example.NativeBase
 
 class PublicClass : NativeBase {
 
-    internal enum class InternalEnum(@JvmField internal val value: Int) {
+    internal enum class InternalEnum(@JvmField @JvmSynthetic internal val value: Int) {
         FOO(0),
         BAR(1);
     }