when the array is an array of object like String we get
java.lang.ClassCastException
at org.drools.base.evaluators.ObjectFactory$ObjectContainsEvaluator.evaluate(ObjectFactory.java:386)
at org.drools.rule.LiteralRestriction.isAllowed(LiteralRestriction.java:61)
at org.drools.rule.LiteralConstraint.isAllowed(LiteralConstraint.java:82)
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:140)
at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:317)
at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:183)
at org.drools.reteoo.Rete.assertObject(Rete.java:121)
at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:196)
at org.drools.reteoo.ReteooWorkingMemory.doAssertObject(ReteooWorkingMemory.java:70)
at org.drools.common.AbstractWorkingMemory.assertObject(AbstractWorkingMemory.java:727)
at org.drools.common.AbstractWorkingMemory.assertObject(AbstractWorkingMemory.java:551)

example: assume we have a class message
class Message{
String [] mess;
}

rule "test"
when
Message(mess contains "HELLO")
then
..
end
the reason is the test in the org.drools.base.ValueType class
else if ( clazz.isAssignableFrom( Object[].class ) ) {
return ValueType.ARRAY_TYPE; the test will be satisfied only for array of java.lang.Object and not for others object
a simple solution is to modify this test in
else if ( clazz.isArray() && clazz.getComponentType() instanceof Object) {
return ValueType.ARRAY_TYPE;