List<String> columnNames = task.getColumns(); ImmutableList.Builder<Column> builder = ImmutableList.builder(); int i = 0; for (String columnName : columnNames) { for (Column inputColumn: inputSchema.getColumns()) { if (inputColumn.getName().equals(columnName)) { Column outputColumn = new Column(i++, columnName, inputColumn.getType()); builder.add(outputColumn); break; } } } Schema outputSchema = n