I guess that adding NullValue.java in adql.parser package would help.
At present time I get the following error working on the adql1.2 branch :
xxx/vollt/src/adql/parser/ADQLQueryFactory.java:580: error: cannot find symbol
public NullValue createNullValue() {
^
symbol: class NullValue
location: class ADQLQueryFactory
I guess that adding NullValue.java in adql.parser package would help. At present time I get the following error working on the adql1.2 branch :
Should I search on another place ?