@Test void unsignedVarintSize_32_largest() {
    // largest to encode is a negative number
    assertThat(WriteBuffer.varintSizeInBytes(Integer.MIN_VALUE))
      .isEqualTo(5);
  }
Uses test data and codepoint wrapping trick from okhttp3.FormBodyTest
zipkin/src/test/java/zipkin2/internal/WriteBufferTest.java