Strip relative paths from java_import output files

androidx.annotation_annotation is used as a test data file, and
converting it from a java_library to a java_library_import causes
the relative path used in the test data path to change. Clear the
relative path in java_import the same way that other java based
modules do.

Bug: 288358614
Test: TestJavaLibraryOutputFileRel
Change-Id: I1f494110da32e916043ca94ac6ebeeafccc06f9a
diff --git a/java/java.go b/java/java.go
index 72536cd..b5f7077 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2555,7 +2555,7 @@
 	// header jar for this module.
 	reuseImplementationJarAsHeaderJar := slices.Equal(staticJars, staticHeaderJars)
 
-	var headerOutputFile android.WritablePath
+	var headerOutputFile android.ModuleOutPath
 	if reuseImplementationJarAsHeaderJar {
 		headerOutputFile = outputFile
 	} else {
@@ -2578,8 +2578,12 @@
 			headerOutputFile = outputFile
 		}
 	}
-	j.combinedHeaderFile = headerOutputFile
-	j.combinedImplementationFile = outputFile
+
+	// Save the output file with no relative path so that it doesn't end up in a subdirectory when used as a resource.
+	// Also strip the relative path from the header output file so that the reuseImplementationJarAsHeaderJar check
+	// in a module that depends on this module considers them equal.
+	j.combinedHeaderFile = headerOutputFile.WithoutRel()
+	j.combinedImplementationFile = outputFile.WithoutRel()
 
 	j.maybeInstall(ctx, jarName, outputFile)