final void require(int byteCount) {
    if (this.available() < byteCount) {
      throw new IllegalArgumentException(
        "Truncated: length " + byteCount + " > bytes available " + this.available());
    }
  }
@return the value read. Use {@link WriteBuffer#varintSizeInBytes(long)} to tell how many bytes.
@throws IllegalArgumentException if more than 64 bits were encoded
zipkin/src/main/java/zipkin2/internal/ReadBuffer.java