Description of problem:

DecisionTableConfigurationImpl.toProperties() throws NPE, when I try to programatically configure Resource's DecisionTableInputType while I am not setting worksheetName (which is optional according to javadoc and should be allowed to be null):

public Properties toProperties() {
    Properties prop = super.toProperties();
    prop.setProperty( DROOLS_DT_TYPE, inputType.toString() );
    prop.setProperty( DROOLS_DT_WORKSHEET, worksheetName );
    return prop;
}

The problem is that prop is a HashTable not allowing null values (worksheetName in this case).

Since there are workarounds for this problem, I am setting severity to medium.

Version-Release number of selected component (if applicable):

Drools 6.0.1-SNAPSHOT
BRMS 6.0.0.ER7

How reproducible:

Try to configure Resource's DecisionTableInputType like this and compile the KieBase:

DecisionTableConfiguration dtConf = new DecisionTableConfigurationImpl();
dtConf.setInputType(type);
resource.setConfiguration(dtConf);

Is there a factory for DecisionTableConfiguration that should be used in this case?

Actual results:

Writing DecisionTableConfiguration into Properties causes NPE and KieBase compilation fails.

Expected results:

KieBase compilation succeeds.