no need for & here

core/document.cpp

@@ -1884,7 +1884,7 @@ void DocumentPrivate::doContinueGooglesDocumentSearch(void *pagesToNotifySet, vo
     }
 }
 
-QVariant DocumentPrivate::documentMetaData( const Generator::DocumentMetaDataKey &key, const QVariant &option ) const
+QVariant DocumentPrivate::documentMetaData( const Generator::DocumentMetaDataKey key, const QVariant &option ) const
 {
     switch ( key )
     {

core/document_p.h

@@ -177,7 +177,7 @@ class DocumentPrivate
          * Request a particular metadata of the Document itself (ie, not something
          * depending on the document type/backend).
          */
-        QVariant documentMetaData( const Generator::DocumentMetaDataKey &key, const QVariant &option ) const;
+        QVariant documentMetaData( const Generator::DocumentMetaDataKey key, const QVariant &option ) const;
 
         /**
          * Return whether the normalized rectangle @p rectOfInterest on page number @p rectPage

core/generator.cpp

@@ -437,7 +437,7 @@ QVariant Generator::documentMetaData( const QString &key, const QVariant &option
     return QVariant();
 }
 
-QVariant Generator::documentMetaData( const DocumentMetaDataKey &key, const QVariant &option ) const
+QVariant Generator::documentMetaData( const DocumentMetaDataKey key, const QVariant &option ) const
 {
     Q_D( const Generator );
     if ( !d->m_document )

core/generator.h

@@ -534,7 +534,7 @@ class OKULARCORE_EXPORT Generator : public QObject
          *
          * @since 1.1
          */
-        QVariant documentMetaData( const DocumentMetaDataKey &key, const QVariant &option = QVariant() ) const;
+        QVariant documentMetaData( const DocumentMetaDataKey key, const QVariant &option = QVariant() ) const;
 
         /**
          * Request a meta data of the Document, if available, like an internal