It's possible to write the "measure" value for a PointZ into a shapefile using JTS' "CoordinateXYZM". To check that it was successful, simply load the file with e.g. QGIS and you'll see all 4 values (x, y, z & m).
Reading the same file it's impossible to get the "m" value again because geotools is ignoring it, instead of passing it through e.g. JTS again.
Affected code: PointHandler.java:
This should probably be instead:
Win 10, Eclipse, Java 8, GeoTools (version "23-SNAPSHOT", downloaded through Maven)