object constructor can take as a parameter object of the same class

frontend-js/src/main/js/map/data/Chemical.js

@@ -3,20 +3,38 @@
 var Annotation = require("./Annotation");
 var TargettingStructure = require("./TargettingStructure");
 
+/**
+ * @typedef {TargettingStructureOptions} ChemicalOptions
+ * @property {Annotation[]} references
+ * @property {string[]} synonyms
+ * @property {string} description
+ * @property {string} directEvidence
+ * @property {Annotation[]} directEvidenceReferences
+ */
+
 /**
  *
- * @param javaObject
+ * @param {ChemicalOptions|Chemical} javaObject
  * @constructor
  */
 function Chemical(javaObject) {
   TargettingStructure.call(this, javaObject);
   if (javaObject !== undefined) {
-    this.setReferences(javaObject.references);
-    this.setDescription(javaObject.description);
-    this.setSynonyms(javaObject.synonyms);
-
-    this.setDirectEvidence(javaObject.directEvidence);
-    this.setDirectEvidenceReferences(javaObject.directEvidenceReferences);
+    if (javaObject instanceof Chemical) {
+      this.setReferences(javaObject.getReferences());
+      this.setDescription(javaObject.getDescription());
+      this.setSynonyms(javaObject.getSynonyms());
+
+      this.setDirectEvidence(javaObject.getDirectEvidence());
+      this.setDirectEvidenceReferences(javaObject.getDirectEvidenceReferences());
+    } else {
+      this.setReferences(javaObject.references);
+      this.setDescription(javaObject.description);
+      this.setSynonyms(javaObject.synonyms);
+
+      this.setDirectEvidence(javaObject.directEvidence);
+      this.setDirectEvidenceReferences(javaObject.directEvidenceReferences);
+    }
   }
 }
 

frontend-js/src/main/js/map/data/MiRna.js

@@ -2,9 +2,13 @@
 
 var TargettingStructure = require("./TargettingStructure");
 
+/**
+ * @typedef {TargettingStructureOptions} MiRnaOptions
+ */
+
 /**
  *
- * @param javaObject
+ * @param {MiRnaOptions|MiRna} javaObject
  * @constructor
  * @extends TargettingStructure
  */