presto-example-http/src/main/java/io/prestosql/plugin/example/ExampleRecordCursor.java/ExampleRecordCursor/getFieldValue
class ExampleRecordCursor:    private String getFieldValue(int field)
    {
        checkState(fields != null, "Cursor has not been advanced yet");

        int columnIndex = fieldToColumnIndex[field];
        return fields.get(columnIndex);
    }