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
StringBuffer buf = new StringBuffer( "\n " + getClass().getSimpleName() + ":" ); 
            buf.append( "; flattenableFieldName: " + m_nestedCollFieldName ); 
            for( Entry<String, FieldMetaData> entry : m_fieldsMetaData.entrySet() )
            {
                buf.append( "\n  field key: " + entry.getKey() ); 
                buf.append( "; metadata: " + entry.getValue() ); 
            }
            return buf.toString();
        }
    }
    /**
     * The metadata of an individual field found in one or more documents 
     * in a collection.
     * A field is uniquely identified by name within a document.
     * If a field value is a sub-document, this includes the sub-document's metadata.
     */
    public class FieldMetaData
    {
        private static final String ARRAY_NOTATION = "[]"; 
        private String m_simpleName;
        private Set<Integer> m_nativeDataTypes;
        private DocumentsMetaData m_childDocMetaData;
        private FieldMetaData m_parentMd;    
        private String[] m_nameFragments;    
 
        private FieldMetaData( String simpleName )
        {
            m_simpleName = simpleName;
        }
        public String getSimpleName()