We've opened the SR-A77131 and we got from Pega the following answer:
«We have checked with our product development team and we came to know that there will not be any impact with this exception.
The reason for this exception is, there is an exception scenario in the normal code flow(which is part of a standard third party tool i.e : apache AXIS) and it is executing the alternate solution/code flow once exception is raised. Because of that we are not writing that error/exception anywhere in the pega related log files.
DynaTrace is great for examining garbage collection because of that it is capturing that exception and showing it. As there is no performance or functional issue with this we can ignore it.»