How to create picketlink identityquery with "NOT" conditions?

Question

I want to query my identities and show it in a table with sorting, pagination and filtering options. It's all ok but i haven't found a way to introduce NOT conditions.

In the code, the T variable is an org.picketlink.idm.model.IdentityType and identityClass is the real class.

IdentityQueryBuilder queryBuilder = getIdentityManager().getQueryBuilder();

IdentityQuery<T> query = queryBuilder.createIdentityQuery(identityClass);
List<Condition> condizioni = new ArrayList<>();
conditions.addAll(conditionFromFilterClausole(queryBuilder, ffc));
Condition c[] = condizioni.toArray(new Condition[condizioni.size()]);
query.where( c);
...

in the method conditionFromFilterClausole i translate some object (FilterClause) in where conditions for identity query. FilterClause.field is the column name, FilterClause.operator is the type of condition and FilterClause.value is the value to use

for(FilterClause f : lf){
    QueryParameter qp = new org.picketlink.idm.query.AttributeParameter(f.getField());
        switch(f.operator){
            case EQUAL:
                conditions.add(qb.equal(qp, f.value));
                break;
            case CONTAINS :
                conditions.add(qb.like(qp, (String) f.value));
                break;
            case ENDSWITH : 
                ???
            case STARTSWITH : 
                ???
                break;
            case GREATEREQUAL : 
                conditions.add( qb.greaterThanOrEqualTo(qp, (String) f.value));
                break;
            case GREATERTHEN : 
                conditions.add(qb.greaterThan(qp, (String) f.value));
                break;
            case LESSEQUAL: 
                conditions.add( qb.lessThanOrEqualTo(qp, (String) f.value));
                break;
            case LESSTHEN: 
                conditions.add(qb.lessThan(qp, (String) f.value));
                break;
            case IN: 
                conditions.add(qb.in(qp, f.value));
                break;
            case NOTIN: 
            case NOTCONTAINS:
            case NOTEQUAL:
                ???
                break;
        }

I miss the way to create conditions for "STARTSWITH/ENDSWITH" and all the other conditions with a NOT, for example the classic not equal (all the case with ???). QueryBuilder hasn't those methods.