Bugfix/5045 : Modified the existing logic to comply crossref resoluti…

…on with biblatex specification (JabRef#5086)

* bugfix/5045 :Modified the existing logic to comply crossref resolution with biblatex specification

* bugfix/5045: Modified the logic to comply crossref resolution with
biblatex spec

* bugfix/5045: Organizes imports

* bugfix/5045: Organized imports.

src/main/java/org/jabref/model/entry/BibEntry.java

@@ -134,12 +134,24 @@ public Optional<String> getResolvedFieldOrAlias(Field field, BibDatabase databas
         }
 
         Optional<String> result = getFieldOrAlias(field);
-
         // If this field is not set, and the entry has a crossref, try to look up the
         // field in the referred entry: Do not do this for the bibtex key.
         if (!result.isPresent() && (database != null)) {
             Optional<BibEntry> referred = database.getReferencedEntry(this);
-            result = referred.flatMap(entry -> entry.getFieldOrAlias(field));
+            if (referred.isPresent()) {
+                result = referred.get().getFieldOrAlias(field);
+                if (!result.isPresent() && type.equals(StandardEntryType.InProceedings)) {
+                    if (field == StandardField.BOOKTITLE) {
+                        result = referred.get().getFieldOrAlias(StandardField.TITLE);
+                    }
+                    else if (field == StandardField.BOOKSUBTITLE) {
+                        result = referred.get().getFieldOrAlias(StandardField.SUBTITLE);
+                    }
+                    else if (field == StandardField.BOOKAUTHOR) {
+                        result = referred.get().getFieldOrAlias(StandardField.AUTHOR);
+                    }
+                }
+            }
         }
         return result.map(resultText -> BibDatabase.getText(resultText, database));
     }