private static Collection<Writer> getAllWriters(final Collection<Writer>[][] matrix) {
		Collection<Writer> writers = Collections.newSetFromMap(new IdentityHashMap<Writer, Boolean>());
		for (int i = 0; i < matrix.length; ++i) {
			for (int j = 0; j < matrix[i].length; ++j) {
				writers.addAll(matrix[i][j]);
			}
		}
		return writers;
	}
private static Collection < Writer > getAllWriters ( final Collection < Writer > [ ] [ ] matrix ) { Collection < Writer > writers = Collections . newSetFromMap ( new IdentityHashMap < Writer , Boolean > ( ) ) ; for ( int i = 0 ; i < matrix . length ; ++ i ) { for ( int j = 0 ; j < matrix [ i ] . length ; ++ j ) { writers . addAll ( matrix [ i ] [ j ] ) ; } } return writers ; }
Collects all writer instances from a matrix of writers.

@param matrix
All writers
@return Collection that contains each writer only once