extension return instance types with appropriate generic type

histream-core/src/main/java/de/sekmi/histream/Extension.java

@@ -58,6 +58,6 @@ public interface Extension<T>{
 	 * TODO change return type to array, to register all compatible classes
 	 * @return instance type
 	 */
-	Class<?>[] getInstanceTypes();
+	Iterable<Class<? super T>> getInstanceTypes();
 	
 }

histream-core/src/main/java/de/sekmi/histream/impl/ClassExtension.java

-package de.sekmi.histream.impl;
-
-import de.sekmi.histream.Extension;
-import de.sekmi.histream.Observation;
-import de.sekmi.histream.ext.IdExtensionType;
-
-/**
- * Extension to allow grouping/classification of facts.
- * This can be seen similar to the {@code class} attribute
- * in HTML which can be given to any element.
- * <p>
- * XXX still need to figure how to serialize the class id
- * to the {@code fact/@class} attribute.
- * </p>
- * 
- * @author R.W.Majeed
- *
- */
-public class ClassExtension implements Extension<ClassExtension.Clazz> {
-
-
-	public static class Clazz implements IdExtensionType{
-		private String id;
-		
-		@Override
-		public String getId() {
-			return id;
-		}
-
-		@Override
-		public void setId(String id) {
-			this.id = id;
-		}
-
-	}
-
-	@Override
-	public Clazz createInstance(Observation observation) {
-		// TODO use modifier "class" to get the class value
-		// otherwise unable to create a class for the given observation
-		throw new UnsupportedOperationException();
-		//return null;
-	}
-
-	@Override
-	public Clazz createInstance(Object... args) throws UnsupportedOperationException, IllegalArgumentException {
-		if( args.length != 1 || !(args[0] instanceof String) ){
-			throw new IllegalArgumentException("Fact extension for class needs exactly one string argument for the class id");
-		}
-		Clazz c = new Clazz();
-		c.setId((String)args[0]);
-		return c;
-	}
-
-	@Override
-	public Class<?>[] getInstanceTypes() {
-		return new Class[]{Clazz.class};
-	}
-
-}

histream-core/src/main/java/de/sekmi/histream/impl/SimplePatientExtension.java

 package de.sekmi.histream.impl;
 
+import java.util.Arrays;
+
 /*
  * #%L
  * histream
@@ -34,10 +36,10 @@ import de.sekmi.histream.ext.Patient;
  *
  */
 public class SimplePatientExtension implements Extension<PatientImpl>{
-	private final static Class<?>[] TYPES = new Class<?>[]{Patient.class, PatientImpl.class};
+	private final static Iterable<Class<? super PatientImpl>> TYPES = Arrays.asList(Patient.class, PatientImpl.class);
 
 	@Override
-	public Class<?>[] getInstanceTypes() {return TYPES;}
+	public Iterable<Class<? super PatientImpl>> getInstanceTypes() {return TYPES;}
 
 	@Override
 	public PatientImpl createInstance(Object... args) {

histream-core/src/main/java/de/sekmi/histream/impl/SimpleVisitExtension.java

@@ -22,16 +22,19 @@ package de.sekmi.histream.impl;
 
 
 import de.sekmi.histream.Observation;
+
+import java.util.Arrays;
+
 import de.sekmi.histream.Extension;
 import de.sekmi.histream.ext.ExternalSourceType;
 import de.sekmi.histream.ext.Patient;
 import de.sekmi.histream.ext.Visit;
 
 public class SimpleVisitExtension implements Extension<VisitImpl>{
-	private final static Class<?>[] TYPES = new Class<?>[]{Visit.class, VisitImpl.class};
+	private final static Iterable<Class<? super VisitImpl>> TYPES = Arrays.asList(Visit.class, VisitImpl.class);
 
 	@Override
-	public Class<?>[] getInstanceTypes() {return TYPES;}
+	public Iterable<Class<? super VisitImpl>> getInstanceTypes() {return TYPES;}
 
 	@Override
 	public VisitImpl createInstance(Object... args) {