logically asserted facts do not get retracted properly

1) Setup the following rules:

rule "#1: value out of range (verification)"
when
val : Value( value > 100 )
then
System.out.println("found invalid value: " + val.getValue());

assertLogical(new Message("value out of range"));
end

rule "#2: value out of range (print out)"
when
Message( message == "value out of range" )
then
System.out.println("value out of range");
end

2) Assert a Value fact that triggers rule #1 (note that the Value Bean provides Property Change Support for its "value" attribute):

// assert fact - invalid value
Value value = new Value(101);
FactHandle handle = workingMemory.assertObject(value);

workingMemory.fireAllRules();

=> Output looks like this:

found invalid value: 101
value out of range
— working memory dump —
class com.sample.Value: value = 101
class com.sample.Message: value out of range

3) Now modify the Value fact:

// modify fact - invalid value
value.setValue(102);
workingMemory.modifyObject(handle, value);

workingMemory.fireAllRules();

=> Output looks like this:

found invalid value: 102
value out of range
— working memory dump —
class com.sample.Value: value = 102
class com.sample.Message: value out of range
class com.sample.Message: value out of range

=> A bit strange here: we have two Message objects - but this could be ok if both objects get retracted after modifying Value fact's value, so that it does not support the truth for rule #1... let's test

4) Modify the value fact again:

// modify fact - valid value
value.setValue(100);
workingMemory.modifyObject(handle, value);

workingMemory.fireAllRules();

=> Output looks like this:

<none>
— working memory dump —
class com.sample.Value: value = 100
class com.sample.Message: value out of range

Conclusion: There is still a Message fact in the working memory that was asserted logically (by rule) due to the fact Value ( value > 100 ), which does not exist any more! The (second) Message fact must be retracted too OR logically asserted facts must be asserted only once (even if the according rule is triggered multiple times). Otherwise the statement in the documentation is incorrect (chapter 3.5.2): "assertLogical(new Something());" is similar to assert, but the object will be automatically retracted when there are no more facts to support the truth of the currently firing rule".