Assuming that you meant to state 'Class Diagram' instead of 'Project Hierarchy', I've used the following Eclipse plug-ins to generate Class Diagrams at various points in my professional career:
Obligatory links
The listed tools will not generate class diagrams from source code, or atleast when I used them quite a few years back. You can use them to handcraft class diagrams though.
Related questions on StackOverflow
Except for ObjectAid and a few other mentions, most of the Eclipse plug-ins mentioned in the listed questions may no longer be available, or would work only against older versions of Eclipse.