title: Javax @NotNull annotation usage
body: <p>I have a simple method to get a list of documents for a given <code>companyId</code>. Here is the method:</p>
  
  <pre><code>@Override
  public List&lt;Documents&gt; getDocumentList(@NotNull Integer companyId) {
      Company company = new Company(companyId);
      return this.documentRepository.findByCompany(company);
  }
  </code></pre>
  
  <p>I wanted to use Javax validation constraints to ensure that the <code>companyId</code> being passed in, is not <code>null</code>. But it seems to not have any effect, as I'm able to pass in a <code>null</code> value, and it flows down to the <code>findByCompany</code> call on the repository. I also added <code>@Valid</code> before <code>@NotNull</code> to force validation, but that too didn't do anything. </p>
  
  <p>I could always write a couple of lines to check for a <code>null</code> value, but wanted to use <code>javax.validation</code> annotations to make the code more readable and concise. Is there a way to make the annotations work on method params?</p>