The following is what is used if the System property is not set for the validation layer:
String validationLayerFactoryClass = System.getProperty("filemgr.validationLayer.factory","org.apache.oodt.cas.validation.DataSourceValidationLayerFactory");
First the default class does not exist "org.apache.oodt.cas.validation.DataSourceValidationLayerFactory" and should be changed to "org.apache.oodt.cas.filemgr.validation.DataSourceValidationLayerFactory". Actually this probably would be better as the following:
String validationLayerFactoryClass = System.getProperty("filemgr.validationLayer.factory", org.apache.oodt.cas.filemgr.validation.XMLValidationLayerFactory.class.getName());
This way the compile time check will be made. As noted above I'm thinking the default for LuceneCatalogFactory should be XML based one and not the DataSource one. Since it was already broken this should not affect backwards compatibility.