Streamline type check in content constructs

outOfLineContent.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"mime"
-	"reflect"
 )
 
 type OutOfLineContent struct {
@@ -20,15 +19,16 @@ func newOutOfLineContent(mediaType string, content any) (*OutOfLineContent, erro
 		return nil, fmt.Errorf("media type %v incompatible with out of line content", mediaType)
 	}
 
-	if reflect.TypeOf(content).Kind() != reflect.String {
+	iri, ok := content.(IRI)
+	if !ok {
 		return nil, fmt.Errorf("content type %T incompatible with out of line content", content)
 	}
 
-	if !isValidIRI(content.(IRI)) {
+	if !isValidIRI(iri) {
 		return nil, errors.New("content not a valid uri")
 	}
 
-	return &OutOfLineContent{Type: MediaType(mediaType), SRC: content.(IRI)}, nil
+	return &OutOfLineContent{Type: MediaType(mediaType), SRC: iri}, nil
 }
 
 // isContent checks whether the OutOfLineContent is a Content. It returns a