I noticed that a recent checkout of the Spring PetClinic Samples application has an error in STS, specifically it complains in the Spring validation on line 72 of applicationContext-hibernate.xml that clinic bean, of type org.springframework.samples.petclniic.hibernate.Hi bernateClinic does not have a constructor with 0 arguments. In fact, that file has no constructors. Amazingly enough, STS will 'quick fix' this and add a stub constructor that removes the error and allows the project to run without problems.
I haven't noticed on prior versions of STS -- perhaps the Validator logic doesn't think java.lang.Objecte's empty constructor counts?
Platform is Ubuntu 9.10, Java 1.6.0_16-b01, STS 2.3.0.RELEASE, check out of petclinic as of 1am 12-30-09.