log/field.go
func Int32(key string, val int32) Field {
	return Field{
		key:        key,
		fieldType:  int32Type,
		numericVal: int64(val),
	}
}
func Int32(key string, val int32) Field {
	return Field{
		key:        key,
		fieldType:  int32Type,
		numericVal: int64(val),
	}
}
// Int32 adds an int32-valued key:value pair to a Span.LogFields() record