I agree with Sanjay.
Sun SCEA document mentions, for instance, "it is not necessary to provide each method name and attribute in the class".
That means they don't want UML diagrams confused and complicated to read.
The human, who will grade you, will check it out :
-UML compliant
-Correct usage of entity CMP/BMP, choice of session stateful/stateless.
-Applicability of design
patterns.
-Consistency of your architecture
-Suggestions
For instance, you can just add a note in your sequence diagram that an exception (application or system, related to transaction)will be log or thrown, and show in your sequence diagram a link to an "error jsp" object.
Don't forget you provide a kind of BluePrint. The FBN CEO has to clearly understand your architecture/Design.
It is not a "reference manual" for the developpers.