@Test void utf8_matchesAscii() {
    String ascii = "86154a4ba6e913854d1e00c0db9010db";
    int encodedSize = WriteBuffer.utf8SizeInBytes(ascii);
    assertThat(encodedSize)
      .isEqualTo(ascii.length());

    byte[] bytes = new byte[encodedSize];
    WriteBuffer.wrap(bytes).writeAscii(ascii);
    assertThat(new String(bytes, UTF_8))
      .isEqualTo(ascii);

    WriteBuffer.wrap(bytes).writeUtf8(ascii);
    assertThat(new String(bytes, UTF_8))
      .isEqualTo(ascii);
  }
Uses test data and codepoint wrapping trick from okhttp3.FormBodyTest
zipkin/src/test/java/zipkin2/internal/WriteBufferTest.java