Trivial Lines 1557-1558:
"The Client Identifier which was assigned by the Server because a zero length Client Identifier was found in the CONNECT packet."
could be deleted since Lines 1560-1562 state the same information in a more precise manner:
"If the Client connects using a zero length Client Identifier, the Server MUST respond with a CONNACK containing an Assigned Client Identifier. The Assigned Client Identifier MUST be a new Client Identifier not used by any other Session currently in the Server ..."