Add hasKey() convenience methods.

src/core/EntryAttachments.cpp

@@ -27,6 +27,11 @@ QList<QString> EntryAttachments::keys() const
     return m_attachments.keys();
 }
 
+bool EntryAttachments::hasKey(const QString& key) const
+{
+    return m_attachments.keys().contains(key);
+}
+
 QList<QByteArray> EntryAttachments::values() const
 {
     return m_attachments.values();

src/core/EntryAttachments.h

@@ -30,6 +30,7 @@ class EntryAttachments : public QObject
 public:
     explicit EntryAttachments(QObject* parent = Q_NULLPTR);
     QList<QString> keys() const;
+    bool hasKey(const QString& key) const;
     QList<QByteArray> values() const;
     QByteArray value(const QString& key) const;
     void set(const QString& key, const QByteArray& value);

src/core/EntryAttributes.cpp

@@ -36,6 +36,11 @@ QList<QString> EntryAttributes::keys() const
     return m_attributes.keys();
 }
 
+bool EntryAttributes::hasKey(const QString& key) const
+{
+    return m_attributes.keys().contains(key);
+}
+
 QList<QString> EntryAttributes::customKeys()
 {
     QList<QString> customKeys;

src/core/EntryAttributes.h

@@ -32,6 +32,7 @@ class EntryAttributes : public QObject
 public:
     explicit EntryAttributes(QObject* parent = Q_NULLPTR);
     QList<QString> keys() const;
+    bool hasKey(const QString& key) const;
     QList<QString> customKeys();
     QString value(const QString& key) const;
     bool isProtected(const QString& key) const;