[JAXRS-SPEC] no @Valid annotation on simple fields

[martin-mfg]

based on #14435 by @anatoliy-balakirev

fix #14432

• The change in beanValidation.mustache is still the same as in 14432: Do not add @Valid to Java types in "jaxrs-spec" generator #14435.
• The change in pojo.mustache had to be adapted a bit, because the file has changed on the master branch in the meantime.
  I also added a small whitespace change to improve the generated code's style a bit. It's still not great though.
• I also added a new unit test in JavaJAXRSSpecServerCodegenTest.java

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[wing328]

It's still not great though.

we recommend users to run linter e.g. spotless to auto format the code based on their preference.

[wing328]

lgtm. thanks for the fix.

have a nice weekend