Download org.wso2.carbon.extension.identity.authenticator.outbound.emailotp : org.wso2.carbon.identity.authenticator.emailotp.feature JAR file - All Versions:
Download JD-GUI to open JAR file and explore Java source code file (.class .java)
Click menu "File → Open File..." or just drag-and-drop the JAR file in the JD-GUI window org.wso2.carbon.identity.authenticator.emailotp.feature-4.1.7.jar file.
Once you open a JAR file, all the java classes in the JAR file will be displayed.