title: How to inherit GORM mapping from non domain class?
body: <p>Permanently I have some tables and some hibernate classes with mapping annotations. And this classes have abstract superclass with mapping annotations also. But in this superclass there is no table association mapping. All tables are identified in the subclasses.
  I'm trying to migrate this mapping to GORM model. But all strategies: TablePerHierarchy and TablePerSubclass not approach for my case because all tables is created and can't be changed.
  I created superclass in the 'src/groovy/somepackage/' and want to inherit mapping and constraints from this class to my subclasses in the 'domain' folder. For constraints it works good but for mapping I can't find documentation how to do this. 
  Does anyone have any ideas?   </p>
  
  <p><strong>Example</strong>.</p>
  
  <p>In the non-domain folder:</p>
  
  <pre><code>absract class A {
    String a
    static mapping = {
      a column: "column_A"
    }
  } 
  </code></pre>
  
  <p>In the domain folder:</p>
  
  <pre><code>class B extends A {
    String b
    static mapping = {
      b column: "column_B"
    }
  }
  </code></pre>
  
  <p>And</p>
  
  <pre><code>class C extends A {
    String c
    static mapping = {
      c column: "column_C"
    }
  }
  </code></pre>
  
  <p>Needs to get two tables with the column 'column_A' in each of them. </p>