Bug 416703 Mongodb : Display correctly the Number data type
data/org.eclipse.birt.data.oda.mongodb/src/org/eclipse/birt/data/oda/mongodb/internal/impl/MDbMetaData.java
*/
        public boolean hasChildDocuments()
        {
            return m_childDocMetaData != null;
        }
        
        public DocumentsMetaData getChildMetaData()
        {
            return m_childDocMetaData != null ?
                        m_childDocMetaData :
                        sm_emptyFields;
        }
        /* (non-Javadoc)
         * @see java.lang.Object#toString()
         */
        @Override
        public String toString()
        {
            StringBuffer buf = new StringBuffer( "name: " + m_simpleName ); 
            buf.append( "; full display name: " + getFullDisplayName() ); 
            buf.append( "; nativeDataTypes: " + m_nativeDataTypes ); 
            String parentName = m_parentMd != null ?
                    m_parentMd.getFullDisplayName() : "null"; 
            buf.append( "; parent field: " + parentName ); 
            buf.append( "; child document metadata: " + m_childDocMetaData ); 
            return buf.toString();
        }
    }
}