@Nullable public static BaggageField getByName(@Nullable TraceContext context, String name) {
    if (context == null) return null;
    return ExtraBaggageContext.getFieldByName(context, validateName(name));
  }
@Test void getByName_context_null() {
    // permits unguarded use of CurrentTraceContext.get()
    assertThat(BaggageField.getByName((TraceContext) null, "foo"))
      .isNull();
  }