Oracle Solution for Error ora-04055

ORA-04055: Aborted: "string" formed a non-REF mutually-dependent cycle with "string".

What triggered the Error:

This compilation was aborted because the library unit that was compiled would have formed a non-REF mutually-dependent cycle with some other library units. This happens when an attempt is made to compile types that have attributes of other types that may participate in a cycle with this type. Example: create type t1; create type t2 (a t1); create type t1 (a t2);

What should we do to fix it:

Break the cycle (possibly by adding a REF or by using another type).