code: def test_create_custom_state_backend(self):
      gateway = get_gateway()
      JConfiguration = (
          gateway.jvm.org.apache.flink.configuration.Configuration
      )
      j_config = JConfiguration()
      j_factory = load_java_class(
          "org.apache.flink.streaming.runtime.tasks."
          "StreamTaskTest$TestMemoryStateBackendFactory"
      ).newInstance()
      context_classloader = (
          gateway.jvm.Thread.currentThread().getContextClassLoader()
      )
      state_backend = _from_j_state_backend(
          j_factory.createFromConfig(j_config, context_classloader)
      )
  
      self.assertIsInstance(state_backend, CustomStateBackend)
  
imports: from pyflink.datastream.state_backend import _from_j_state_backend, CustomStateBackend, MemoryStateBackend, FsStateBackend, RocksDBStateBackend, PredefinedOptions, EmbeddedRocksDBStateBackend
  from pyflink.java_gateway import get_gateway
  from pyflink.pyflink_gateway_server import on_windows
  from pyflink.testing.test_case_utils import PyFlinkTestCase
  from pyflink.util.java_utils import load_java_class
label_desc: Use image node_id 1 for calling the CustomStateBackendTests obj's underlying member method code with example usage: obj.test_create_custom_state_backend() without return types