Keeps, of a raw value read from a link, what may be per-field entries: a map of non-empty
strings, capped in number, key length and value length.
Parameters
raw: unknown
What a compact payload carried under fieldFilters, or the gl_f.*
parameters gathered from a verbose link.
Returns Record<string,string>|undefined
The entries, or undefined when there is none to keep.
Security
The keys come from a URL. A key that would reach the prototype is dropped, and
the result is built key by key — never spread from the untrusted object.
Keeps, of a raw value read from a link, what may be per-field entries: a map of non-empty strings, capped in number, key length and value length.