replace Collections.sort() by List.sort()

[hduelme]

Since java 8 List.sort() can be used instead of Collections.sort() to sort an list.
I also refactor getDefaultStrategies to directly return Collections.emptyList(); if the result of defaultStrategies.getProperty(key) is null. This reduces the complexity of the method and prevent the not needed call to sort() for Collections.emptyList().

[gregturn]

Thanks @hduelme!