title: Using ConfigurationProperties to fill Map in generic way
body: <p>I'm wondering, if there is a generic way to fill a map with properties you just know the prefix.</p>
  
  <p>Assuming there are a bunch of properties like</p>
  
  <pre><code>namespace.prop1=value1
  namespace.prop2=value2
  namespace.iDontKnowThisNameAtCompileTime=anothervalue
  </code></pre>
  
  <p>I'd like to have a generic way to fill this property inside a map, something like</p>
  
  <pre><code>@Component
  @ConfigurationProperties("namespace")
  public class MyGenericProps {
      private Map&lt;String, String&gt; propmap = new HashMap&lt;String, String&gt;();
  
      // setter and getter for propmap omitted
  
      public Set&lt;String&gt; returnAllKeys() {
          return propmap.keySet();
      }
  }
  </code></pre>
  
  <p>Or is there another convenient way to collect all properties with a certain prefix, instead of iterating over all PropertySources in the environment?</p>
  
  <p>Thanks
  Hansjoerg</p>