Test.java

public class Test {

    /**
     * Unable to Analyse Expression this.getName() == "joe":
     * [Error: unable to resolve method using strict-mode: org.drools.compiler.oopath.MyTest$Parent.getName()]
     * [Near : {... this.getName() == "joe" ....}]
     * ^
     * [Line: 4, Column: 2] : [Rule name='R']
     */

    @Test
    public void test() {
        final String drl =
            "import "+ Parent.class.getCanonicalName() +";\n" +
                "import "+ Child.class.getCanonicalName() +";\n" +
                "rule R " +
                "when\n" +
                    // using [name==\"joe\"] works OK
                    "  Parent( $child : /children, $child.getName() == \"joe\" )\n" +
                "then\n" +
                    "  System.out.println( $child );\n" +
                "end\n";

        final KieSession ksession = new KieHelper().addContent( drl, ResourceType.DRL )
            .build()
            .newKieSession();

        Child joe = new Child("joe");
        Child jack = new Child("jack");
        Parent parent = new Parent(Arrays.asList(joe, jack));

        ksession.insert(parent);
        ksession.fireAllRules();
    }

    public class Child {
        private String name;
        public Child(String name) {
            this.name = name;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String toString() {
            return this.name;
        }
    }

    public class Parent {
        private List<Child> children;
        public Parent(List<Child> children) {
            this.children = children;
        }
        public List<Child> getChildren() {
            return children;
        }
        public void setChildren(List<Child> children) {
            this.children = children;
        }

        // If this is uncommented, the rule works

        //public String getName() {
        //    return "definitelyNotJoe";
        //}
    }

}