Eclipse 4.4.2 does not recognize trait Interfaces on scala singleton objects in Java code

BugDemo.java

/**
 * This class demonstrates that Eclipse 4.4.2 for some reason does not recognize
 * that the Scala singleton object for the class Implementor does in fact
 * implement the interface Interface<String>.
 * 
 * Instead, it shows the error markers mentioned in the comments.
 * 
 * However, the code compiles fine (by the Eclipse compiler!), and in fact
 * running this class' main method prints:
 * 
 * <pre>
 * Hello World
 * Hello World
 * Hello World
 * Hello World
 * </pre>
 * 
 * 
 * 
 */
public class BugDemo {

  public static void main(String[] args) {
    testParameter();
    testAssignment();
    testCast();
    testObjectCast();
  }
  
  /**
   * "The method print(Interface<String>) in the type Caller is not applicable
   * for the arguments (Implementor$)"
   */
  private static void testParameter() {
    print(Implementor.ref());
//  ^^^^^
  }

  /**
   * "Type mismatch: cannot convert from Implementor$ to Interface<String>"
   */
  private static void testAssignment() {
    Interface<String> foo = Implementor.ref();
//                          ^^^^^^^^^^^^^^^^^
    print(foo);
  }
  
  /**
   * "Cannot cast from Implementor$ to Interface<String>"
   */
  private static void testCast() {
    print((Interface<String>) Implementor.ref());
//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  }
  
  /**
   * This one works, obviously.
   */
  private static void testObjectCast() {
    Object foo = Implementor.ref();
    print((Interface<String>) foo);
  }


  private static void print(Interface<String> foo) {
    System.out.println(foo.someMethod());
  }
}

Implementor.scala

trait Interface[T] {
  def someMethod: T
}

object Implementor extends scala.AnyRef with Interface[String] {
  def someMethod: String = "Hello World"
  
  def ref: this.type = this
}


/**
 * To make things even stranger, if I add the following code to Implementor.scala,
 * all the beforementioned errors become a Warning "Type safety: The expression of 
 * type Implementor$ needs unchecked conversion to conform to Interface<String>".
 * 
 * This does NOT happen if I put it in a separate file (e.g. "Test.scala")
 */
object Test {
}