code: def default_java_namespace(self, target):
      
      self._check_target(target)
      return target.default_java_namespace or self._default_default_java_namespace
docs: Returns the default_java_namespace used for Thrift generation.
  
      :param target: The target to extract the default_java_namespace from.
      :type target: :class:`pants.backend.codegen.targets.java_thrift_library.JavaThriftLibrary`
      :returns: The default Java namespace used when not specified in the IDL.
      :rtype: string