code: public CoalesceUnit getUpdatedCoalesceUnit(final InputColumn<?>[] newInputColumns) {
          if (Arrays.equals(_inputColumns, newInputColumns)) {
              return this;
          } else {
              return new CoalesceUnit(newInputColumns);
          }
      }
docs: Creates new {@link CoalesceUnit} if {@link InputColumn}s has changed
  
  @param newInputColumns List of new {@link InputColumn}s
  @return New {@link CoalesceUnit} if {@link InputColumn}s has truly changed, otherwise this.