beam property
Beam membership of this note, as an input hint.
Set it yourself to encode beams explicitly (and set
Measure.autoBeaming = false, or use BeamingMode.manual, so the
automatic grouping leaves your value alone).
Since 2.7.2 the layout NEVER writes here. It publishes its own decision as
a value on LayoutEngine.beams / LayoutEngine.tupletBeams, and
LayoutEngine.beamOf(note) is the only supported read: it returns the
engine's answer when the engine made one and falls back to this field when
it did not. See doc/adr/ADR-005-layout-decisions-are-values.md.
Until 2.7.1 the engine did stamp its answer back in place, which made a
pure export depend on whether the score had been displayed: MEASURED on
two bars of loose quavers, the same Staff exported 3 349 characters with
0 <beam> tags before layout() and 3 973 with 16 after. Both are
byte-identical now.
Implementation
BeamType? beam;