### Question:
ColumnPermutation implements Serializable { @Override public boolean equals(Object obj) { if (this == obj) { return true; } if (obj == null) { return false; } if (getClass() != obj.getClass()) { return false; } ColumnPermutation other = (ColumnPermutation) obj; if (columnIdentifiers == null) { if (other.columnIdentifiers != null) { return false; } } else if (!columnIdentifiers.equals(other.columnIdentifiers)) { return false; } return true; } ColumnPermutation();  ColumnPermutation(ColumnIdentifier... columnIdentifier); List<ColumnIdentifier> getColumnIdentifiers(); void setColumnIdentifiers(List<ColumnIdentifier> identifiers); @Override String toString(); String toString(Map<String, String> tableMapping, Map<String, String> columnMapping); static ColumnPermutation fromString(Map<String, String> tableMapping, Map<String, String> columnMapping, String str); @Override int hashCode(); @Override boolean equals(Object obj);  }### Answer:
@Test public void testConstructor() { final ColumnIdentifier expectedColumn1 = new ColumnIdentifier("table1", "column1"); final ColumnIdentifier expectedColumn2 = new ColumnIdentifier("table2", "column2"); final ColumnPermutation columnPermutation = new ColumnPermutation(expectedColumn1, expectedColumn2, expectedColumn2); assertEquals(3, columnPermutation.columnIdentifiers.size()); assertTrue(columnPermutation.columnIdentifiers.get(0).equals(expectedColumn1)); assertTrue(columnPermutation.columnIdentifiers.get(1).equals(expectedColumn2)); assertTrue(columnPermutation.columnIdentifiers.get(2).equals(expectedColumn2)); }