Placeholder API txt file that is used in the java_sdk_library_import modules
in the Android.bp file for their current_api and removed_api properties.

This is not a valid API txt file and is not intended to be used as such. Any
attempt to parse its contents will fail. That is intentional.

Its purpose is simply to allow Soong to pass dependency checking when
TARGET_BUILD_APPS is set without UNBUNDLED_BUILD_SDKS_FROM_SOURCE being set to
true. Without this file being referenced from the java_sdk_library_import
properties any attempt to depend on say ":javax.obex{.public.api.txt}" would
fail in Soong when building with TARGET_BUILD_APPS set and so prevent the
building of any module even those that do not depend on that missing API file.

With this file being referenced from the java_sdk_library_import properties
Soong will pass its dependency checks and produce the ninja file and so allow
modules that do not depend on this file to be built successfully. Building
modules that depend on this file will fail when those modules attempt to parse
this file.