Delay considering the U_HEAD issuing time as context time

It's certainly better than nothing, but it doesn't contain a timezone,
while the enclosing PDF document can.

This is inspired by similar handling for the pkpass relevant date field.

src/lib/processors/uic9183documentprocessor.cpp

@@ -35,13 +35,20 @@ ExtractorDocumentNode Uic9183DocumentProcessor::createNodeFromData(const QByteAr
 
     ExtractorDocumentNode node;
     node.setContent(p);
-
-    const auto u_head = p.findBlock<Uic9183Head>();
-    node.setContextDateTime(u_head.issuingDateTime());
-
     return node;
 }
 
+void Uic9183DocumentProcessor::expandNode(ExtractorDocumentNode &node, [[maybe_unused]] const ExtractorEngine *engine) const
+{
+    // only use the U_HEAD issuing time as context if we have nothing better
+    // while that is usually correct it cannot contain a time zone, unlike the (often) enclosing PDF document´
+    if (!node.contextDateTime().isValid()) {
+        const auto p = node.content<Uic9183Parser>();
+        const auto u_head = p.findBlock<Uic9183Head>();
+        node.setContextDateTime(u_head.issuingDateTime());
+    }
+}
+
 void Uic9183DocumentProcessor::preExtract(ExtractorDocumentNode &node, [[maybe_unused]] const ExtractorEngine *engine) const
 {
     const auto p = node.content<Uic9183Parser>();

src/lib/processors/uic9183documentprocessor.h

@@ -17,6 +17,7 @@ class Uic9183DocumentProcessor : public ExtractorDocumentProcessor
 public:
     bool canHandleData(const QByteArray &encodedData, QStringView fileName) const override;
     ExtractorDocumentNode createNodeFromData(const QByteArray &encodedData) const override;
+    void expandNode(ExtractorDocumentNode &node, const ExtractorEngine *engine) const override;
     void preExtract(ExtractorDocumentNode &node, const ExtractorEngine *engine) const override;
 };