Incorrect resolution of global symbols in LHS rule constraint (Java dialect)

As described @ http://drools.46999.n3.nabble.com/Incorrect-resolution-of-global-symbols-in-LHS-rule-constraint-Java-dialect-tp4027921.html.

I upgraded from 5.5.0.Final of Drools (rule engine) to 5.6.0.Final and I am now seeing errors with globals.

We have rule constraints that access globals in a DRL; like this:

some.classpath.package2.MyType ( global_instance.invoke(this) == true ) 

I have

some.classpath.package.SomeType global_instance;

declared at the top of the DRL, but it doesn't seem to be interpreting it as a global in the rule's restriction.

So, putting this into context within, I have a DRL such as:

package my.package.example;

global some.classpath.package.SomeType global_instance;

rule "Example rule" 
when 
   some.classpath.package2.MyType ( global_instance.invoke(this) == true ) 
then 
   // do something 
end 

I am getting an error from the package builder originating from the "Example rule" specifying something like:
"can't find method MyType.global_instance()"

Once, again this did work in 5.5.0.Final, but in 5.6.0.Final I am getting a failure trying to build the knowledge package.
It looks to me like the global_instance symbol is not being recognized as a global in the DRL and is trying to be
resolved as a method of the MyType class.
So I guess it would be trying to do a "MyType.global_instance().invoke(this)" or something.

The intent is that global_instance will be set for a session with an immutable function-type of class
(invoke is an instance method though; not static). The rule restriction uses this function/predicate to determine if some
complex criteria is true for `this` MyType instance.

I would appreciate any insight into what the issue might be. I haven't been able to find any threads out there on a similar issue.