public void clear() throws CacheException {
            LOGGER.trace("Clearing all objects from cache [{}]", cache.getName());
            try {
                cache.removeAll();
            } catch (Throwable t) {
                throw new CacheException(t);
            }
        }
Removes all elements in the cache, but leaves the cache in a useable state.
support/jcache/src/main/java/org/apache/shiro/cache/jcache/JCacheManager.java