setterKey static method
The name a SETTER is bound under: Dart's own setter name, v=.
A getter and a setter of one name are two declarations, and binding both
under the plain name made the second replace the first. The setter lives
under v=, which no identifier can spell, so a bare read of v finds the
getter and a bare write asks for v= (SCF25).
Implementation
static String setterKey(String name) => '$name=';