Extract toTagSet interface

src/main/java/fr/igred/omero/annotations/Tag.java

@@ -0,0 +1,14 @@
+package fr.igred.omero.annotations;
+
+
+@FunctionalInterface
+public interface Tag {
+
+    /**
+     * Converts this tag annotation to a tag set.
+     *
+     * @return See above.
+     */
+    TagSet toTagSet();
+
+}

src/main/java/fr/igred/omero/annotations/TagAnnotation.java

@@ -24,7 +24,7 @@
 /**
  * Interface to handle Tag Annotations on OMERO.
  */
-public interface TagAnnotation extends Annotation {
+public interface TagAnnotation extends Tag, Annotation {
 
     /**
      * The name space used to indicate that the tag is used a tag set.
@@ -68,12 +68,4 @@ default boolean isTagSet() {
         return NS_TAGSET.equals(getNameSpace());
     }
 
-
-    /**
-     * Converts this tag annotation to a tag set.
-     *
-     * @return See above.
-     */
-    TagSet toTagSet();
-
 }