jhat has support for reachability analysis -- objects that are reachable from a given object are shown as a page. Also, Object Query Language (refer to 6321810) supports reachables built-in function to return reachable objects as an array. jhat provides -exclude command line option to filter a set of fields (specified in a file as class_name.field_name form) to be omitted when computing reachable objects. It is better to provide similar but flexible field filtering in OQL reachables function. For eg. comma separated excluded fields may be accepted as an argument to reachables.