The case its trying to access 'isAssignable' and fails with Assertion, I was expecting a false return value.
 Comparing ()void with ()void
  ()void Assignable ()void
 Comparing ()void with (java.lang.String)void


An annotation processor threw an uncaught exception.
Consult the following stack trace for details.
java.lang.AssertionError: isSubType 12
        at com.sun.tools.javac.code.Types$5.visitType(Types.java:345)
        at com.sun.tools.javac.code.Types$5.visitType(Types.java:430)
        at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visitMethodType(Types.java:2871)
        at com.sun.tools.javac.code.Type$MethodType.accept(Type.java:783)
        at com.sun.tools.javac.code.Types$DefaultTypeVisitor.visit(Types.java:2867)
        at com.sun.tools.javac.code.Types.isSubType(Types.java:307)
        at com.sun.tools.javac.code.Types.isSubTypeUnchecked(Types.java:285)
        at com.sun.tools.javac.code.Types.isConvertible(Types.java:254)
        at com.sun.tools.javac.code.Types.isAssignable(Types.java:1398)
        at com.sun.tools.javac.code.Types.isAssignable(Types.java:1359)
        at com.sun.tools.javac.model.JavacTypes.isAssignable(JavacTypes.java:77)
        at CaseAP.process(CaseAP.java:29)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:497)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.discovery(JavacProcessingEnvironment.java:421)
        at com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:569)
        at com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:843)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:629)
        at com.sun.tools.javac.main.Main.compile(Main.java:756)
        at com.sun.tools.javac.main.Main.compile(Main.java:681)
        at com.sun.tools.javac.main.Main.compile(Main.java:670)
        at com.sun.tools.javac.Main.compile(Main.java:70)
        at com.sun.tools.javac.Main.main(Main.java:55)
java version "1.6.0-auto"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-auto-292b)
Java HotSpot(TM) Server VM (build 1.6.0-ea-b56, mixed mode)

Annotation processor and input java file for are used.
$JAVA_HOME/bin/javac -classpath $CLASSPATH -processor CaseAP Case1.java
bash-3.00$ cat Case1.java
public class Case1 {
    public void doMethod2_1(String message){
        System.out.println(" message "+message);
    }
}
bash-3.00$ cat CaseAP.java
import java.util.*;
import javax.annotation.processing.*;
import javax.lang.model.element.*;
import javax.lang.model.type.*;
import javax.lang.model.util.*;
import static javax.lang.model.SourceVersion.*;
import static javax.lang.model.type.TypeKind.*;

@SupportedAnnotationTypes("*")
@SupportedSourceVersion(RELEASE_6)
@SupportedOptions("-verbose")
public class CaseAP extends AbstractProcessor {
    public void init(ProcessingEnvironment penv) {
        super.init(penv);
    }
    public boolean process(Set<? extends TypeElement> typeElementSet,
            RoundEnvironment renv) {
        Vector<TypeMirror> listArrayElementList = new Vector<TypeMirror>();
        for( TypeElement element : renv.getSpecifiedTypeElements()) {
            List<? extends Element > list = element.getEnclosedElements();
            for( Element e : list) {
                listArrayElementList.add(e.asType());
            }
            listArrayElementList.add(element.asType());
        }
        for(TypeMirror mirror : listArrayElementList) {
            for (TypeMirror mirror_ : listArrayElementList) {
                System.out.println(" Comparing "+mirror.toString() +" with "+mirror_.toString());
                if ( processingEnv.getTypeUtils().isAssignable(mirror_, mirror) ) {
                    System.out.println(" "+mirror.toString()+
                            " Assignable "+mirror_.toString() );
                } else {
                    System.out.println(" "+mirror.toString()+
                            " not Assignable "+mirror_.toString() );
                }
            }
        }
        return true ;
    }
}
bash-3.00$


Please do see attached files with this CR.