code: def _get_gatk_opts(config, names, tmp_dir=None, memscale=None, include_gatk=True, parallel_gc=False):
      
      if include_gatk and "gatk4" in dd.get_tools_off({"config": config}):
          opts = ["-U", "LENIENT_VCF_PROCESSING", "--read_filter",
                  "BadCigar", "--read_filter", "NotPrimaryAlignment"]
      else:
          opts = []
      jvm_opts = ["-Xms750m", "-Xmx2g"]
      for n in names:
          resources = config_utils.get_resources(n, config)
          if resources and resources.get("jvm_opts"):
              jvm_opts = resources.get("jvm_opts")
              break
      if memscale:
          jvm_opts = config_utils.adjust_opts(jvm_opts, {"algorithm": {"memory_adjust": memscale}})
      jvm_opts += get_default_jvm_opts(tmp_dir, parallel_gc=parallel_gc)
      return jvm_opts + opts
docs: Retrieve GATK memory specifications, moving down a list of potential specifications.