[Java] Add missing imports for Set in java clients

Created by: languitar

In case of array properties declared with uniqueItems: true, the generated Java code uses Sets but imports are not present for them in the Api and Test classes.

Maybe this can be considered for a bugfix release also for older releases?

CC @bbdouglas @sreeshas @jfiala @lukoyanov @cbornet @jeff9finger @karismann @Zomzog @lwlee2608 @nmuesch

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• Read the contribution guidelines.
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  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh

  Commit all changed files. This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master. These must match the expectations made by your contribution. You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*. For Windows users, please run the script in Git BASH.
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changed title from Add missing imports for Set in microprofile client to Add missing imports for Set in java clients

changed title from Add missing imports for Set in java clients to [Java] Add missing imports for Set in java clients

added Client: Java Issue: Bug labels

changed milestone to %5.3.0

closed