@classmethod
def build(cls, *, uri, display_name=None, parameters=None, tag=None):
    """Build a new Header from kwargs."""
    self = object.__new__(cls)
    self._uri = uri
    self._display_name = display_name
    self._parameters = parameters if parameters else {}
    if tag:
        self._parameters['tag'] = tag
    self._validate()
    return self
