Fixed ignoring javax.validation.constraints.NotNull annotation when using @Schema

[altro3]

Fixed #660

[altro3]

@ilopmar @graemerocher Hi! I fixed several bugs and maybe we can realese these changes. Can you review them? I'm talking about these pull requests: #724, #723, #722, #721, #719, #717, #666, #606

[ilopmar]

@altro3 Hi, I'm not involved in Micronaut anymore. I'll let Graeme and the rest of the team review them. Thanks :)

[altro3]

@ilopmar Thanks! Good luck with new projects! :-)

[graemerocher]

There are test failures

[altro3]

@graemerocher thanks! all problems fixed

[graemerocher]

Thanks for the contribution!