ProtoSourcesProvider
      check_deps_sources
        depset ProtoSourcesProvider.check_deps_sources
    Proto sources from the 'srcs' attribute. If the library is a proxy library that has no sources, it contains the check_deps_sources from this library's direct deps.
        
direct_descriptor_set
        File ProtoSourcesProvider.direct_descriptor_set
    The 
FileDescriptorSet of the direct sources. If no srcs, contains an empty file.
        
direct_sources
        list ProtoSourcesProvider.direct_sources
    Proto sources from the 'srcs' attribute.
        
transitive_descriptor_sets
        depset ProtoSourcesProvider.transitive_descriptor_sets
    A set of 
FileDescriptorSet files of all dependent proto_library rules, and this one's. This is not the same as passing --include_imports to proto-compiler. Will be empty if no dependencies.
        
transitive_imports
        depset ProtoSourcesProvider.transitive_imports
    Transitive imports including weak dependencies.
        
transitive_proto_path
        depset ProtoSourcesProvider.transitive_proto_path
    A set of proto source roots collected from the transitive closure of this rule.
        
transitive_sources
        depset ProtoSourcesProvider.transitive_sources
    Proto sources for this rule and all its dependent protocol buffer rules.