A code lens represents a Command that should be shown along with source text, like the number of references, a way to run tests, etc.
A code lens is unresolved when no command is associated to it. For performance reasons the creation of a code lens and resolving should be done to two stages.
The range in which this code lens is valid. Should only span a single line.
The command this code lens represents.
true when there is a command associated.