Fixes#11649 - As noted in the issue, when CommandNodes are serialized
they are used as the key in a Map. Their equals()/hashcode() should only match if they are equal nodes (name & command), but due to the erasure of the command field pre-serialization, nodes with different commands can be mapped onto the same value. This causes the client to interpret both nodes as the same, causing suggestions where they should not.
This is fixed by creating a different no-op command for the
erasure, instead of them holding the same lambda.
