Library Compatibility with Protobuf-Java 4.26.x+

[lqiu96]

Protobuf has released v26.x+ which introduces a bunch of breaking changes for Protobuf-Java. Release notes for the version can be found at https://github.com/protocolbuffers/protobuf/releases/tag/v26.0

We have identified a removed method that should be updated:

• TextFormat.printToString():

  java-datastore/google-cloud-datastore/src/main/java/com/google/cloud/datastore/Key.java

  Line 148 in 13d9af1

  return URLEncoder.encode(TextFormat.printToString(toPb()), UTF_8.name());

  . This functionality was removed in via this commit: protocolbuffers/protobuf@dfb8a4c

See this doc for more information.