private long toUnsignedLong(int x) {
    return ((long) x) & 0xffffffffL;
  }
Static method to create a JsonKeysetWriter that writes to a file path.

<p>This method only works on Android API level 26 or newer.

@deprecated Method should be inlined.
java_src/src/main/java/com/google/crypto/tink/JsonKeysetWriter.java