Fact metadata declared in a POJO are lost when declaring fact metadata in DRL

Assume a POJO is used as a fact and annotated with @Position as follows:

public class PositionAnnotatedEvent {

@Position(1)
private String arg1;

@Position(0)
private String arg0;

// getters and setters
}

When I add some metadata to this class in DRL, for example:

declare org.jboss.qa.brms.bre.regression.POJOAnnotationMergeTest.PositionAnnotatedEvent
@role(event)
end

Then the following rule using positional arguments does not compile, producing an IndexOutOfBoundsException with message 'Error trying to access field at position 0'. The same rule with named arguments compiles:

rule 'sample rule'
when
org.jboss.qa.brms.bre.regression.POJOAnnotationMergeTest.PositionAnnotatedEvent( 'value1', 'value2'; )
then
end

The relevant stack trace follows:

java.lang.IndexOutOfBoundsException: Error trying to access field at position 0
at org.drools.factmodel.ClassDefinition.getField(ClassDefinition.java:162)
at org.drools.rule.builder.PatternBuilder.processPositional(PatternBuilder.java:432)
at org.drools.rule.builder.PatternBuilder.processConstraintsAndBinds(PatternBuilder.java:392)
at org.drools.rule.builder.PatternBuilder.build(PatternBuilder.java:310)
at org.drools.rule.builder.PatternBuilder.build(PatternBuilder.java:131)
at org.drools.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:65)
at org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:80)
at org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:2578)
at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:970)
at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:456)
at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:643)
at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:41)