tests/alltypes_proto3_callback/alltypes.options - third_party/github/nanopb/nanopb - Git at Google

 # Generate all fields as callbacks.
 AllTypes.*              type:FT_CALLBACK
 SubMessage.substuff1    max_size:16
 AllTypes.oneof          no_unions:true

 # With FT_CALLBACK, these options should get ignored
 *.*fbytes fixed_length:true max_size:4
	# Generate all fields as callbacks.
	AllTypes.* type:FT_CALLBACK
	SubMessage.substuff1 max_size:16
	AllTypes.oneof no_unions:true

	# With FT_CALLBACK, these options should get ignored
	.fbytes fixed_length:true max_size:4