I tried compile vaadin-gwt-polymer-elements:1.2.1.0' and vaadin-gwt-polymer-elements:1.2.3.0' with GWT 2.7 with jsInteropMode = "JS":
Here is the error I get:
[WARN] Warnings in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/paper/widget/PaperTabsBase.java'
[WARN] Line 28: Referencing method 'com.vaadin.polymer.Polymer.onReady': method 'com.vaadin.polymer.Polymer.onReady(Lcom/google/gwt/dom/client/Element;Ljava/lang/Object;)' is deprecated
Tracing compile failure path for type 'com.vaadin.polymer.elemental.Function'
[ERROR] Errors in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/elemental/Function.java'
[ERROR] Line 6: JsFunction cannot be resolved to a type
[ERROR] Line 3: The import com.google.gwt.core.client.js.JsFunction cannot be resolved
Tracing compile failure path for type 'com.vaadin.polymer.iron.IronAutogrowTextareaElement'
[ERROR] Errors in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/iron/IronAutogrowTextareaElement.java'
[ERROR] Line 393: JsType methods cannot overload another method.
Tracing compile failure path for type 'com.vaadin.polymer.neon.HeroAnimationElement'
[ERROR] Errors in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/neon/HeroAnimationElement.java'
[ERROR] Line 126: JsType methods cannot overload another method.
Tracing compile failure path for type 'com.vaadin.polymer.neon.OpaqueAnimationElement'
[ERROR] Errors in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/neon/OpaqueAnimationElement.java'
[ERROR] Line 87: JsType methods cannot overload another method.
Tracing compile failure path for type 'com.vaadin.polymer.iron.IronInputElement'
[ERROR] Errors in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/iron/IronInputElement.java'
[ERROR] Line 208: JsType methods cannot overload another method.
Tracing compile failure path for type 'com.vaadin.polymer.polymer.BaseElement'
[ERROR] Errors in 'jar:file:/Users/mg/.gradle/caches/modules-2/files-2.1/com.vaadin.polymer/vaadin-gwt-polymer-elements/1.2.1.0/fbd8404e9995cebdbf0417b244654b58278ba3f1/vaadin-gwt-polymer-elements-1.2.1.0.jar!/com/vaadin/polymer/polymer/BaseElement.java'
[ERROR] Line 740: JsType methods cannot overload another method.
I tried compile vaadin-gwt-polymer-elements:1.2.1.0' and vaadin-gwt-polymer-elements:1.2.3.0' with GWT 2.7 with
jsInteropMode = "JS"
:Here is the error I get: