Seems like a duplicate of 4346874 but this time a simple solution is provided.

Rich, the developer here who works most with the introspector has been
trying to fix a bug recently that occurs where users create a class that
has the same name as one that exists that has a BeanInfo class defined for
it. For example, suppose there is the class somepackage.WindowBeanInfo
that is in the introspector's search path designed to provide the
descriptors for java.awt.Window. The user may create their own class
called com.mycorp.myapp.Window, and what occurs is that the introspector
picks up the WindowBeanInfo class designed for the AWT class. This is
causing us problems because the property sheet shows the wrong set of
details, the icon and customizer are from the wrong class, etc.... The
best fix seems to be in the Introspector itself that actually checks the
value of getBeanClass() in the bean descriptor before using the incorrect
BeanInfo as a match.