static String writeAscii(long v) {
    byte[] bytes = new byte[WriteBuffer.asciiSizeInBytes(v)];
    WriteBuffer.wrap(bytes).writeAscii(v);
    return new String(bytes, UTF_8);
  }
Uses test data and codepoint wrapping trick from okhttp3.FormBodyTest
zipkin/src/test/java/zipkin2/internal/WriteBufferTest.java