sS str_shortenSyntheticAndStandardToString(O o) {
  if (o == null) ret "null";
  if (isInstanceOfSyntheticClass(o)) ret "Synthetic instance of " + joinWithSlash(map(c -> "interface " + shortClassName(c), o.getClass().getInterfaces()));
  if (o instanceof Class) ret "class " + shortName(o);
  if (isArray(o))
    ret arrayElementType(o) + "[" + arrayLength(o) + "]";
  if (!implementsCustomToString(o)) ret "Instance of " + shortClassName(o);
  ret str(o);
}

Began life as a copy of #1030054