Default blackboard entry does not create entry for locked content

[zflat]

Describe the bug

Using the method getLockedPortContent with a node that declares the port with a default blackboard entry does not actually add an initial value to the blackboard.

How to Reproduce

The first time that getLockedPortContent is called for a key that is not added to the blackboard already, the call does not create any blackboard entry. It returns a default AnyPtrLocked which is not placed into the blackboard storage.

For example, an action can declare a port with default blackboard entry name like InputPort<Pointcloud>("cloud", "{=)", "Point cloud"). Then in the action it can access the locked content and assign it.

if(auto any_locked = getLockedPortContent("cloud"))
{
  if(any_locked->empty())
  {
    // the entry in the blackboard hasn't been initialized yet.
    // You can initialize it doing:
    any_locked.assign(my_initial_pointcloud);
  }

But unless the XML declares the port explicitly, the value returned from getLockedPortContent will not actually be a value from blackboard storage and so the call to any_locked.assign does not persist the assignment after any_locked goes out of scope.

I think that one resolution is to create the blackboard entry in the call to getLockedPortContent if there is a mapped key.

AnyPtrLocked Blackboard::getAnyLocked(const std::string& key)
{
  if(auto entry = getEntry(key))
  {
    return AnyPtrLocked(&entry->value, &entry->entry_mutex);
  }
+ else if (auto entry = createEntryIfValidKey(key))
+ {
+   return AnyPtrLocked(&entry->value, &entry->entry_mutex);
+ }
  return {};
}

Workaround

Without fixing the issue, the port must be declared in the XML

<AcquirePointCloud cloud="{=}" />

[facontidavide]

So, I am not sure if I agree with your suggested change, I need to think about this more carefully.

Can you create a PR with a (failing) unit test where the "issue" is being reproduced, i.e. the expected behavior?