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
* @param ofField   field name
         * @return  a set of known MongoDB native data type codes
         */
        public Set<Integer> getNativeDataTypes()
        {
            if( m_nativeDataTypes == null )
                return Collections.emptySet();
            return m_nativeDataTypes;
        }
 
        private Integer getScalarNativeDataType()
        {
            Set<Integer> nativeDataTypes = getNativeDataTypes();
            for( Integer nativeDataType : nativeDataTypes )
            {
                if( nativeDataType == Integer.valueOf(BSON.ARRAY) ||
                    nativeDataType == Integer.valueOf(BSON.OBJECT) )
                    continue;   
                return nativeDataType;  
            }
            return null;    
        }
        public boolean isArrayOfScalarValues()
        {
            if( ! hasArrayDataType() )
                return false;
            return ! hasDocumentDataType(); 
        }
        public boolean isArrayOfDocuments()
        {