class_docstr: Base class for test table sink.
code: def _ensure_initialized(cls):
      if TestTableSink._inited:
          return
  
      FLINK_SOURCE_ROOT_DIR = _find_flink_source_root()
      filename_pattern = "flink-python/target/flink-python*-tests.jar"
      if not glob.glob(
          os.path.join(FLINK_SOURCE_ROOT_DIR, filename_pattern)
      ):
          raise unittest.SkipTest(
              "'flink-python*-tests.jar' is not available. Will skip the related tests."
          )
  
      gateway = get_gateway()
      java_import(
          gateway.jvm,
          "org.apache.flink.table.utils.TestingSinks$TestAppendingSink",
      )
      java_import(
          gateway.jvm,
          "org.apache.flink.table.utils.TestingSinks$RowCollector",
      )
  
      TestTableSink._inited = True
  
imports: import glob
  import os
  import unittest
  from py4j.java_gateway import java_import
  from pyflink.find_flink_home import _find_flink_source_root
  from pyflink.java_gateway import get_gateway
  from pyflink.table.sinks import TableSink
  from pyflink.table.types import _to_java_data_type
  from pyflink.util import java_utils
label_desc: Use image node_id 2 for calling the TestTableSink obj's underlying member method code with example usage: obj._ensure_initialized(cls) without return types