If the native query returns tuple containing null values, then NativeQueryTupleTransformer throws IllegalArgumentException with the message "Unknown alias [aliasName]", where aliasName is the name of the column having null value. For instance, "aliasToValue" contains
entries
<id, 1>
<value, null>
For this case "Unknown alias [value]" will be shown.

Bug is caused by:

Object tupleElement = aliasToValue.get( alias.toLowerCase() );
  if ( tupleElement == null ) {
	throw new IllegalArgumentException( "Unknown alias [" + alias + "]" );
  }

which returns null for the key which is present in the map, but the value itself is null.

Suggested fix:
We have to check if the key is present in "aliasToValue" map via "containsKey" method.