@Nullable private static DruidJsonFilter toSimpleDruidFilter(RexNode e, RelDataType rowType, DruidQuery druidQuery) { switch (e.getKind()) { case EQUALS: case NOT_EQUALS: return toEqualityKindDruidFilter(e, rowType, druidQuery); case GREATER_THAN: case GREATER_THAN_OR_EQUAL: case LESS_THAN: case LESS_THAN_OR_EQUAL: return toBoundDruidFilter(e, rowType, druidQuery); case BETWEEN: return toBetweenDruidFilter(e, rowType, druidQuery); case IN: case NOT_IN: return toInKindDruidFilter(e, rowType, druidQuery); case IS_NULL: case IS_NOT_NULL: return toIsNullKindDruidFilter(e, rowType, druidQuery); default: return null; } }