Today, you can set a custom name to a field using the @Name annotation, or by passing the name to the ValueDescriptor class when creating a dynamic event. For example:

class Transaction extends Event {
   @Name("foo")"
   int _lousy_field_name;
}
var e = new Transaction();
...

var fields = new ArrayList<ValueDescriptor>();
fields.add(new ValueDescriptor(int.class, "foo"));
var f = EventFactory.create("Transaction". List.of(), fields);
var e = f.newEvent();
...

The ValueDescriptor constructor states that the name must be valid, but an IllegalArgumentException is not thrown when the object is created.
 The @Name annotation states that the name must be a valid Java identifier, but it's not enforced when the event class is registered.

This can be problematic if trying to reconstruct events as classes, for example in a parser, if class and field names are not valid. Furthermore, if the fields are used to output data, for example a CSV file, for a plotting utility it will break if spaces, tabs or newlines can be used. The expectations is that field, event and settings names are valid.