code: def _string_to_varchar_holder(ra, string):
      nvch_cls = "org.apache.arrow.vector.holders.NullableVarCharHolder"
      holder = jpype.JClass(nvch_cls)()
      if string is None:
          holder.isSet = 0
      else:
          holder.isSet = 1
          value = jpype.JClass("java.lang.String")("string")
          std_charsets = jpype.JClass(
              "java.nio.charset.StandardCharsets"
          )
          bytes_ = value.getBytes(std_charsets.UTF_8)
          holder.buffer = ra.buffer(len(bytes_))
          holder.buffer.setBytes(0, bytes_, 0, len(bytes_))
          holder.start = 0
          holder.end = len(bytes_)
      return holder
  
file_path: arrow/python/pyarrow/tests/test_jvm.py
imports: import json
  import os
  import pyarrow
  import pyarrow.jvm
  import pytest
  import sys
  import xml.etree.ElementTree
label_desc: Use image node_id 10 for calling a global function with example usage: _string_to_varchar_holder(ra, string) and returns: holder