Quoting documentation:

Field	Type	Description
value	number (for numeric items) or string (for text items)	Collected item value.
type	number	Collected value type: 0 - numeric float, 1 - character, 2 - log, 3 - numeric unsigned, 4 -text

(Not related to the issue, but note that there is a lack of space in "-text".)
And then there example follows:

Numeric (float) value:

{"host":{"host":"Host B","name":"Host B visible"},"groups":["Group X","Group Y","Group Z"],"applications":["CPU","Performance"],"itemid":4,"name":"CPU Load","clock":1519304285,"ns":123456789,"value":"0.1","type":0}

So the protocol description says that value must be "number (for numeric items)", but the example for "Numeric (float) value" has value as string ("value":"0.1") despite type saying that it should be numeric ("type":0 i.e. "0 - numeric float").

P.S. I have not checked the actual behaviour. Maybe it's just a wrong example, maybe something worse.