added com.sap.sse.security.common which bundles security-related stuff that is shared by Java7 GWT projects as well as Java8 backend projects

java/com.sap.sse.security.common/src/com/sap/sse/security/shared/UserManagementException.java

@@ -0,0 +1,28 @@
+package com.sap.sse.security.shared;
+
+import java.io.Serializable;
+
+public class UserManagementException extends Exception implements Serializable {
+
+    private static final long serialVersionUID = 7555799541580565866L;
+    
+    public static final String USER_DOES_NOT_EXIST = "User does not exist";
+    public static final String USER_ALREADY_EXISTS = "User already exists";
+    public static final String INVALID_CREDENTIALS = "Invalid Credentials";
+    public static final String PASSWORD_DOES_NOT_MEET_REQUIREMENTS = "Password does not meet requirements";
+    public static final String USERNAME_DOES_NOT_MEET_REQUIREMENTS = "Username does not meet requirements";
+    public static final String CANNOT_RESET_PASSWORD_WITHOUT_VALIDATED_EMAIL = "Cannot reset password without validated e-mail address";
+
+    public UserManagementException() {} // for GWT serialization
+    
+    private String message;
+    
+    @Override
+    public String getMessage() {
+        return message;
+    }
+
+    public UserManagementException(String message) {
+        this.message = message;
+    }
+}