Some of its methods use the inheritDoc tag and some do not. In particular the following methods do not, and their wording differs only slightly from the corresponding wording that could be inherited from the Map interface:

putIfAbsent()
remove(key, value)
replace(key, value)
replace(key, oldValue, newValue)

Sometimes the ConcurrentMap doc includes a code snippet and additional text such as "except that the action is performed atomically." This can remain and augment the inherited doc.

Note that JDK-8159527 will add the "(optional operation)" wording to some mutator methods where it was missing. This wording will be inherited by the existing ConcurrentMap methods where inheritDoc is already used; it will be inherited by more if usage of inheritDoc is expanded.

It's not clear to me that mutator methods of a ConcurrentMap are in fact optional. If we want to remove the "(optional operation)" wording from ConcurrentMap, we'll need to investigate doing something other than adding inheritDoc tags.