QueryResult.get fires ClassCastException when using the string argument

here is the simple test case:

package simpletest;

public class AssertedObject {
private String value;

public String getValue()

{ return value; }

public void setValue(String value)

{ this.value = value; }

public AssertedObject(String value)

{ // TODO Auto-generated constructor stub this.value = value; }

}

package simpletest;

import simpletest.AssertedObject;

rule rule1
when
then
assert( new AssertedObject( "value1") );
assert( new AssertedObject( "value2") );
end

query "assertedobjquery"
assertedobj : AssertedObject( value=="value1" )
end

package simpletest;

import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import mit.rules.test.Prestazione;
import mit.rules.test.StrutturaErogante;
import mit.rules.test.TempiAttesa;
import mit.rules.test.TestRules;

import org.drools.QueryResult;
import org.drools.QueryResults;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.WorkingMemory;
import org.drools.audit.WorkingMemoryFileLogger;
import org.drools.compiler.PackageBuilder;

public class TestQuery {
public static void main(String[] args) throws Exception

{ // TODO Auto-generated method stub final PackageBuilder builder = new PackageBuilder(); builder.addPackageFromDrl( new InputStreamReader( TestQuery.class.getResourceAsStream( "testquery.drl" ) ) ); final RuleBase ruleBase = RuleBaseFactory.newRuleBase(); ruleBase.addPackage( builder.getPackage() ); final WorkingMemory workingMemory = ruleBase.newWorkingMemory(); fireRules(workingMemory); }

public static void fireRules(WorkingMemory workingMemory) {
final WorkingMemoryFileLogger logger = new WorkingMemoryFileLogger( workingMemory );
logger.setFileName( "log/testquery" );

workingMemory.fireAllRules();
QueryResults results = workingMemory.getQueryResults( "assertedobjquery" );

if (results==null || !results.iterator().hasNext())

{ System.err.println("Empty list"); }

else {
for ( Iterator it = results.iterator(); it.hasNext(); )

{ QueryResult result = ( QueryResult )it.next();; AssertedObject assertedObject=(AssertedObject)result.get( "assertedobj" ); System.out.println("AssertedObject with value " + assertedObject.getValue()); }

}
logger.writeToDisk();
}
}