Java, improves schema generics

[spacether]

Java, improves schema class generics

• changes from 6 generics to 3 generics InType, CastType, OutType
• makes one validator interface for each json type, 6 total
• JsonSchema instances must implement getNewInstance that ingests Object and returns Object
  • this allows calls by getNewInstance after validation has been run to convert from cast data types to output data types

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  mvn 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/python*.
  For Windows users, please run the script in Git BASH.