Adding option to include sources only for Java 11 builds

Bug: 207852002
Test: m
Test: EXPERIMENTAL_TARGET_JAVA_VERSION_11=true m
Change-Id: I554a79798ea7f1dd4a96b09f761090f83a009cb4
diff --git a/android/config.go b/android/config.go
index bf79a03..d759fe0 100644
--- a/android/config.go
+++ b/android/config.go
@@ -658,6 +658,10 @@
 	return value == "0" || value == "n" || value == "no" || value == "off" || value == "false"
 }
 
+func (c *config) TargetsJava11() bool {
+	return c.IsEnvTrue("EXPERIMENTAL_TARGET_JAVA_VERSION_11")
+}
+
 // EnvDeps returns the environment variables this build depends on. The first
 // call to this function blocks future reads from the environment.
 func (c *config) EnvDeps() map[string]string {