Printing hairpins using al niente notation

Hairpin dynamics may be printed with a circled tip (“al niente” notation) by setting the circled-tip property of the Hairpin object to #t.

\version "2.24.0"

\relative c'' {
  \override Hairpin.circled-tip = ##t
  c2\< c\!
  c4\> c\< c2\!
}