function mergeDefinitionSource(mDefinitions, mDefinitionSource, mSourceData, oSource) {
		if (mSourceData) {
			for (var sName in mDefinitions) {
				if (!mDefinitionSource[sName] && mSourceData[sName] && mSourceData[sName].uri) {
					mDefinitionSource[sName] = oSource;
				}
			}
		}
	}
Utility function which merges a map of property definitions to track
from which "source" a property was defined.

This function is used to find out which Component has defined
which "dataSource/model".

@param {object} mDefinitions Map with definitions to check
@param {object} mDefinitionSource Object to extend with definition - source mapping
@param {object} mSourceData Actual map with definitions
@param {object} oSource Corresponding source object which should be assigned to the definitions-source map
@private