RANGER-5017: updated sources to address 'may produce NullPointerException' warning, and remove unnecessary generic parameters

[mneethiraj]

What changes were proposed in this pull request?

Updated sources to address following warnings/suggestions from IDE:

• may produce NullPointerException
• remove unnecessary generic parameters

How was this patch tested?

Build with unit tests completed successfully.

[vyommani]

The code changes look good to me. However, I do have a question: were the changes made manually, or did you update the code style plugin to use the diamond operator (<>) and perform null checks manually?

[mneethiraj]

The code changes look good to me. However, I do have a question: were the changes made manually, or did you update the code style plugin to use the diamond operator (<>) and perform null checks manually?

IDE (IntellJ) flags potential NPE warnings, and suggests using <> operator while instantiating generic types. Tjese changes will need to be made manually though.