LSP communicates through JSON so there is no native integer type. To compensate for that we have a custom type def integer.
LSP does not make any statements about additional json extensions, so I assume that standard JSON semantics apply, which would mean that a number serialized as 1.0 is semantically equivalent a number serialized as 1 and thus a valid integer.
This is documented for Json Schema, but since LSP does not use Json Schema in contrast to DAP, I'd like to confirm that the same applies to LSP as well.
I'd also be great to have this clarification added to the description of integer as well.