class_docstr: Base builder to construct a ElasticsearchSink.
class_docstr_tok: ["Base","builder","to","construct","a","ElasticsearchSink","."]
docstr: Sets the username used to authenticate the connection with the Elasticsearch cluster.
code: def set_connection_username(
      self, username: str
  ) -> "ElasticsearchSinkBuilderBase":
      """
      Sets the username used to authenticate the connection with the Elasticsearch cluster.
      """
      self._j_elasticsearch_sink_builder.setConnectionUsername(username)
      return self
  
imports: import abc
  from enum import Enum
  from typing import List, Union
  from pyflink.datastream.connectors import Sink, DeliveryGuarantee
  from pyflink.java_gateway import get_gateway
  from pyflink.util.java_utils import to_jarray
label_desc: Use image node_id 10 for calling the ElasticsearchSinkBuilderBase obj's underlying member method code with example usage: obj.set_connection_username(username) and returns: self