Parametrized queries don't work in DSL

When expanding rule file containing definition of query with parameters I get from knowledge builder 'Unable to expand: (Person p)'.

Steps to Reproduce:
1. add included dsl and dslr files to KnowledegBuilder
2. check that KnowledgeBuilder.getErrors() returns reported problem

dslr file:
package org.jboss.qa.drools.features

import org.jboss.qa.drools.domain.Person

query "isMature"(Person p)
There is a person

• age is greater than 18
• equals p
  end

dsl file:
[when]There is a person=Person()
[when]-

{field:\w*} {operator} {value:\d*}={field}

{operator}

{value}

[when]- equals

{variable}=this := {variable}

[when]is greater than=>