you have to sign the JAR
There are many ways by which you can sign a JAR file for example use jarsigner. You can sign a JAR file using jarsigner like this:
jarsigner -keystore C:\working\mystore -signedjar sbundle.jar bundle.jar john
On executing the command, you will be prompted for the store password and the private key password. Here, bundle.jar represents the jar file you'd like to sign using the private key of the user whose keystore alias is "john" in the keystore named "mystore" located in the directory c:\working.