Configuration.getPropsWithPrefix no longer does variable substitution

Before HADOOP-13556, Configuration.getPropsWithPrefix() used the Configuration.get() method to get the value of the variables. After HADOOP-13556, it now uses props.getProperty().

The difference is that Configuration.get() does deprecation handling and more importantly variable substitution on the value. So if a property has a variable specified with ${variable_name}, it will no longer be expanded when retrieved via getPropsWithPrefix().

Was this change in behavior intentional? I am using this function in the fix for MAPREDUCE-7069, but we do want variable expansion to happen.