When creating an uber-jar with all dependencies in one single-jar file, each of the spring dependency jar may contain schema and handlers that have the same name but different content. When you combine them into creating a single uber-jar, the uber-library will perform an overwrite since each of the Spring files for schema and handlers are the exact filename. So you end up overwriting the file where the last ubered file will remain.
The answer is a lot simpler than you think. But before we explore the answer, I should warn you that this approach is not what is recommended by Maven. Maven builds upon consistency and structure and this process goes away from that methodology. In Maven, you can take each of your jars\libraries and add them to your local repository and then include them as needed in your projects. If you want to go the proper route here’s how you do it.
With a lot of folks trying Google Web Toolkit (GWT) and\or Vaadin (combined with Maven), one of the problems that they might encounter is this: How do I get my custom Vaadin themes or GWT jar files included under my "\web-inf\lib" folder inside the war Here’s a link to the such a question in detail. The answer is a lot simpler than you think. But before we explore the answer, I should warn you that this approach is going away from what Maven would like you to do.