JPA ManyToMany with Eclipselink & GSON circular reference causing a stack overflow after server restart

I have an issue with a manytomany bi-directional JPA relationship that is causing a stack overflow error

when the server is restarted (if there is data in the 3 tables that comprise the manytomany relationship.)

While I have a total of 5 entities in my application, I believe the issue is only related to

the Users and Application entities which use use a bi-directional manytomany relationship.

I have included the JPA diagram containing all entities for completeness

Below are the 2 entities that I believe are causing my circular reference stack overflow:

Application

User

An Application can have many developers

A User can develop many applications

Here is how they are mapped:

//Application Entity:

@ManyToMany

private List<Users> users

//User Entity

@ManyToMany(mappedBy = "users", fetch = FetchType.LAZY)

private List <Applications> applications;

This results in 3 tables being created in the database as shown below:

APPLICATIONS

APPLICATION_USERS < Join table created by JPA when using a ManyToMany relationship.

USERS

The application works fine when it is first deployed with empty tables.

A user registers for an application and this creates a row in the APPLICATIONS table (if the Application does not exist)

A row is also created in the USERS table if the user does not exist and the join table APPLICATION_USERS

is populated with the ID FROM THE APPLICATION Table called APPLICATIONS_ID and

an ID from the USERS table called USERS_ID as shown above.

You can add as many applications or users as you wish and the application works perfectly.

I have verified that data is being loaded and persisted into the 3 tables exactly as expected

Here is an example of the data in the tables after a user registers an Application:

Here is the problem:

Whenever the server is stopped and restarted or when the application is re-deployed using create-tables

(vs drop-and-create-tables) (and data is present in the tables). Application gets a stack overflow at each entities toString() function.

I have run this in debug with a breakpoints on the Applications toString() function and on the Users toString() function and I can click resume and watch each toString() function get called over and over until the stack overflow results.

Here is the console log:

//Entity query being executed

[EL Fine]: 2014-01-21 14:48:44.383--ServerSession(1615948530)--Connection(49767657)--Thread(Thread[http-bio-8080-exec-9,5,main])--SELECT t1.ID, t1.APPIDENTIFIER, t1.DATECREATED, t1.DATEMODIFIED, t1.DEVICETYPE FROM APPLICATIONS_Users t0, APPLICATIONS t1 WHERE ((t0.users_ID = ?) AND (t1.ID = t0.applications_ID))

//second entity query is invoked

[EL Fine]: 2014-01-21 14:50:02.444--ServerSession(1615948530)--Connection(1871047709)--Thread(Thread[http-bio-8080-exec-9,5,main])--SELECT t1.ID, t1.DATECREATED, t1.DATEMODIFIED, t1.EMAIL, t1.FIRSTNAME, t1.FULLNAME, t1.LASTLOGINDATE, t1.LASTNAME, t1.USERNAME FROM APPLICATIONS_Users t0, Users t1 WHERE ((t0.applications_ID = ?) AND (t1.ID = t0.users_ID))

[EL Finest]: 2014-01-21 14:50:02.471--ServerSession(1615948530)--Connection(1601422824)--Thread(Thread[http-bio-8080-exec-9,5,main])--Connection released to connection pool [read].

java.lang.StackOverflowError

at java.util.Vector.get(Vector.java:693)

at java.util.AbstractList$Itr.next(AbstractList.java:345)

at java.util.AbstractCollection.toString(AbstractCollection.java:421)

at java.util.Vector.toString(Vector.java:940)

at org.eclipse.persistence.indirection.IndirectList.toString(IndirectList.java:797)