Add back the api_srcs argument

This arg provides the ability to pass sources to the metalava
invocations that are part of a java_sdk_library without affecting
the runtime library.

This is useful in various scenarios, e.g.: when javadoc in some source
files affects the metalava behavior. For example, the javadoc-generation
javadoc tags @paramDoc, @returnDoc etc. Passing these as a library does
not work because class files do not contain javadoc.

Bug: 186197911
Test: manually inspect module stub src for doc enhancements
Merged-In: I2ce98f891283514e1896c52d9335550c1f5435fb
Change-Id: I2ce98f891283514e1896c52d9335550c1f5435fb
diff --git a/java/sdk_library.go b/java/sdk_library.go
index ce8f179..b00a0f2 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -376,6 +376,9 @@
 }
 
 type sdkLibraryProperties struct {
+	// List of source files that are needed to compile the API, but are not part of runtime library.
+	Api_srcs []string `android:"arch_variant"`
+
 	// Visibility for impl library module. If not specified then defaults to the
 	// visibility property.
 	Impl_library_visibility []string
@@ -1438,6 +1441,7 @@
 	props.Name = proptools.StringPtr(name)
 	props.Visibility = childModuleVisibility(module.sdkLibraryProperties.Stubs_source_visibility)
 	props.Srcs = append(props.Srcs, module.properties.Srcs...)
+	props.Srcs = append(props.Srcs, module.sdkLibraryProperties.Api_srcs...)
 	props.Sdk_version = module.deviceProperties.Sdk_version
 	props.System_modules = module.deviceProperties.System_modules
 	props.Installable = proptools.BoolPtr(false)