@Test void throwsRuntimeExceptionAsReasonWhenPresent() {
    String response = """
      {
        "error": {
          "type": "search_phase_execution_exception",
          "reason": "all shards failed",
          "phase": "query"
        },
        "status": 400
      }
      """;

    assertThatThrownBy(
      () -> CHECK_FOR_ERRORS.convert(JSON_FACTORY.createParser(response), () -> response))
      .isInstanceOf(RuntimeException.class)
      .hasMessage("all shards failed");
  }
Tests lack of a root cause won't crash
zipkin-storage/elasticsearch/src/test/java/zipkin2/elasticsearch/internal/BulkCallBuilderTest.java