feat: Add first version of the 'annotatable' interface

gemeinsamforschen/src/main/java/unipotsdam/gf/interfaces/Annotatable.java

+package unipotsdam.gf.interfaces;
+
+/**
+ * @author Sven Kästle
+ * skaestle@uni-potsdam.de
+ */
+public interface Annotatable {
+
+    /**
+     * Adds an annotation to a document and returns the new id
+     *
+     * @param userId The id of the author of the annotation
+     * @param annotation The annotation as an Object
+     * @return Returns the id of the new annotation
+     */
+    String addAnnotation(String userId, Object annotation);
+
+    /**
+     * Alters an annotation
+     *
+     * @param id The id of the annotation
+     * @param annotation The annotation as an Object
+     */
+    void alterAnnotation(String id, Object annotation);
+
+    /**
+     * Deletes an annotation
+     *
+     * @param id The id of the annotation
+     */
+    void deleteAnnotation(String id);
+
+    /**
+     * Returns a specific annotation from a document
+     *
+     * @param id The id of the annotation
+     * @return Returns a specific annotation
+     */
+    Object getAnnotation(String id);
+
+    /**
+     * Return all annotations from a document
+     *
+     * @return Returns all annotations
+     */
+    Object[] getAnnotations();
+
+}