Update TokenUtils.java

[anderuraga]

check null values

Changes

Please describe both what is changing and why this is important. Include:

• Endpoints added, deleted, deprecated, or changed
• Classes and methods added, deleted, deprecated, or changed
• Screenshots of new or changed UI, if applicable
• A summary of usage if this is a new feature or change to a public API (this should also be added to relevant documentation once released)
• Any alternative designs or approaches considered

References

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• support ticket
• community post
• StackOverflow post
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Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• [ ] This change adds test coverage
• [ ] This change has been tested on the latest version of Java or why not

Checklist

• [ ] I have read the Auth0 general contribution guidelines
• [ ] I have read the Auth0 Code of Conduct
• [ ] All existing and new tests complete without errors