Release google-http-java-client v1.28.0

[chingor13]

This pull request was generated using releasetool.

01-03-2019 14:04 PST

Important Changes

• This library now support Java 7, 8, and 11 (dropped Java 6 support)
• If you are using the apache adapter, please include either the google-http-client-apache or google-http-client-apache-legacy artifacts.

Implementation Changes

• Fix iterable maps JSON serialization (#550)
• Update OpenCensus deprecations (#556)
• Fixed MockBackOff#getMaxTries, returns maxTries (#548)
• Fix building HttpResponseException when charset is malformed (#535)
• Fix UriTemplate.expand to properly escape value (#534)
• GenericData can now overload setters (#538)
• Make signature of com.google.api.client.util.Data#nullOf more type safe (#537)
• Request charset defaults to UTF-8, Response charset defaults to ISO_8859_1 (#532)

New Features

• Re-add OpenCensus integration (#545)
• Re-add Apache PATCH request (#547)
• Split http apache artifact (#543)
• Compile to Java 1.7 binary (#542)
• Implement Closeable & Flushable in JsonGenerator and JsonParser (#540)

Deprecations

• Deprecate JdoDataStoreFactory (#553)
• Deprecate AndroidHttp compatibility shim (#541)
• Deprecate google-http-client-jackson (#539)

Dependencies

• Update commons-codec 1.10 -> 1.11 (#552)
• Update guava to 26.0-android (#531)

Documentation

Internal / Testing Changes

• Use maven enforcer plugin for maven version requirements (#555)
• Need to specify versions for antrun-plugin or it doesn't run (#554)
• Cleanup samples (#544)