void (@NotNull String groupName, @NotNull NavigatableMessageElement navigatableMessageElement) { synchronized (myLock) { List<NavigatableMessageElement> elements = myGroupNameToMessagesMap.get(groupName); if (elements == null) { elements = new ArrayList<>(); myGroupNameToMessagesMap.put(groupName, elements); } if (!myGroupNameToElementMap.containsKey(groupName)) { myGroupNames.add(groupName); myGroupNameToElementMap.put(groupName, navigatableMessageElement.getParent()); } elements.add(navigatableMessageElement); } }