a question about using soapUI API, urgency!

hi, everyone!
i'm a student, trying to collect web service endpoints and oprations.
i have downloaded more than 20.000 WSDL documents.
now i'm trying to call soapUI APIs to parsing these documents.
the code is like follows:

WsdlProject project = new WsdlProject();
WsdlInterface[] iface = WsdlInterfaceFactory.importWsdl(project, WSDLFilePath, true);

though i can get endpoints and oprations by iface, i find that after calling this API, memory resources are occupied and never returned.
if i parse WSDL documents sequentially, program will report out of memory sometime.

what should i do to release memory?

thanks a lot!