code: public TableDefinition getInverseTableDef() {
          assert isLinkType();
          Utils.require(m_tableDef != null, "Field has not been assigned to a table");
          return m_tableDef.getAppDef().getTableDef(m_linkExtent);
      }
docs: Get the {@link TableDefinition} of this field's extent table, which is the table
  that owns its inverse link. This field definition must be a link field. Null is
  returned if the inverse table has not been defined in this application.
  
  @return  {@link TableDefinition} of this link's inverse link's owning table or
  null if it has not been defined in this application.