Something like this

gistfile1.txt

//You'd create this helper AuthoratativePropertilesFileAccessor that would wire in 
// SqlitePropertiesAccessor. Once it's proven that the test is valid we can simply
// delete this class and wire in immediately SqlitePropertiesAccessor

public AuthoratativePropertilesFileAccessor implements PropertiesFileAccessor {

private final PropertiesFileAccessor authoriative;
private final PropertiesFileAccessor test;

public String getProperty(String key) {
 String valueAuth = authorative.getProperty(key);
 String valueTest = authoritative.getProperty(key);
 emitEventIfNotEqual(valueAuth,valueTest);
 return valueAuth;
}

}


public SqlitePropertiesAccessor implements PropertiesFileAccessor {
//
}