[Java][Jaxrs][Resteasy] add @Valid to getter methods, updated

[martin-mfg]

closes #1698

This PR is based on @tnmtechnologies' work in #2039. On top of their changes I made some whitespace changes, to address the remaining comments in #2039.

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[wing328]

FYI. You can do the following to avoid a blank line if useBeanValidation is not true

{{#useBeanValidation}}
import javax.validation.Valid;
{{/useBeanValidation}}