function _getProtocolType(oModel) {
		if (oModel) {
			if (oModel.isA("sap.ui.model.odata.v2.ODataModel")) {
				return mProtocolType.v2;
			} else if (oModel.isA("sap.ui.model.odata.v4.ODataModel")) {
				return mProtocolType.v4;
			}
		}

		return null;
	}
Get protocol type of an oData model

@private
@param {object} oModel - oData model
@returns {string} <code>mProtocolType.v2</code>, <code>mProtocolType.v4</code> or <code>null</code>