Expose flag "--enforce_proguard_file_extension" to Starlark.

It will be used in android_binary rule Starlark migration.

PiperOrigin-RevId: 583146492
Change-Id: Ie40e657f8a8237c0318facb0b3d057d801a14ff6

src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java

diff --git a/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java b/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
index e712507..37e5def 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/java/JavaConfiguration.java
@@ -356,6 +356,7 @@
   }
 
   /** Returns whether ProGuard configuration files are required to use a *.pgcfg extension. */
+  @Override
   public boolean enforceProguardFileExtension() {
     return enforceProguardFileExtension;
   }

src/main/java/com/google/devtools/build/lib/starlarkbuildapi/java/JavaConfigurationApi.java

diff --git a/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/java/JavaConfigurationApi.java b/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/java/JavaConfigurationApi.java
index 8739c9e..9bbf7eb 100644
--- a/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/java/JavaConfigurationApi.java
+++ b/src/main/java/com/google/devtools/build/lib/starlarkbuildapi/java/JavaConfigurationApi.java
@@ -147,4 +147,13 @@
               + " optimizer into. Note that if split_bytecode_optimization_pass is set, this will"
               + " only change behavior if it is > 2.")
   int bytecodeOptimizationPassActions();
+
+  @StarlarkMethod(
+      name = "enforce_proguard_file_extension",
+      structField = true,
+      doc =
+          "Returns whether ProGuard configuration files outside of third_party/ are required to use"
+              + " a *.pgcfg extension.",
+      documented = false)
+  boolean enforceProguardFileExtension();
 }