function (oInstance, sMetaPath, mTypeForMetaPath) {
			var aFilters = [],
				sKey,
				mKey2Value = _Helper.getKeyProperties(oInstance, sMetaPath, mTypeForMetaPath);

			if (!mKey2Value) {
				return undefined;
			}
			for (sKey in mKey2Value) {
				aFilters.push(sKey + " eq " + mKey2Value[sKey]);
			}

			return aFilters.join(" and ");
		}
function (oInstance, sMetaPath, mTypeForMetaPath) {
			var aFilters = [],
				sKey,
				mKey2Value = _Helper.getKeyProperties(oInstance, sMetaPath, mTypeForMetaPath);

			if (!mKey2Value) {
				return undefined;
			}
			for (sKey in mKey2Value) {
				aFilters.push(sKey + " eq " + mKey2Value[sKey]);
			}

			return aFilters.join(" and ");
		}
function ( oInstance , sMetaPath , mTypeForMetaPath ) { var aFilters = [ ] , sKey , mKey2Value = _Helper . getKeyProperties ( oInstance , sMetaPath , mTypeForMetaPath ) ; if ( ! mKey2Value ) { return undefined ; } for ( sKey in mKey2Value ) { aFilters . push ( sKey + " eq " + mKey2Value [ sKey ] ) ; } return aFilters . join ( " and " ) ; }
Returns a filter identifying the given instance via its key properties.

@param {object} oInstance
Entity instance runtime data
@param {string} sMetaPath
The absolute meta path of the given instance
@param {object} mTypeForMetaPath
Maps meta paths to the corresponding entity or complex types
@returns {string}
A filter using key properties, e.g. "Sector eq 'DevOps' and ID eq 42)", or undefined,
if at least one key property is undefined
@throws {Error}
In case the entity type has no key properties according to metadata
Returns a filter identifying the given instance via its key properties .
Returns the filter string for the given key