code: def namespace_map(self, target):
      
      self._check_target(target)
      return target.namespace_map or self._default_namespace_map
docs: Returns the namespace_map used for Thrift generation.
  
      :param target: The target to extract the namespace_map from.
      :type target: :class:`pants.backend.codegen.targets.java_thrift_library.JavaThriftLibrary`
      :returns: The namespaces to remap (old to new).
      :rtype: dictionary