Update curie formation logic (#750)

* - Update curie formation logic

* - Improve code logic

* - Improve code logic to handle edge cases

dataload/rdf2json/src/main/java/uk/ac/ebi/rdf2json/annotators/ShortFormAnnotator.java

@@ -36,16 +36,21 @@ public static void annotateShortForms(OntologyGraph graph) {
 			}
 
 			String shortForm = extractShortForm(graph, ontologyBaseUris, preferredPrefix, c.uri);
-			String curie = shortForm.replaceFirst("_", ":");
 
+			/*
+			CURIEs are formed by following rules:
+			If there is only one underscore "_" AND the characters after the underscore are numbers then replace the underscore with colon ":"
+			If there is only one underscore "_" and the characters after the underscore are not just numbers then just keep the curie same as shortform
+			If there are multiple underscore but has only digits after the last underscore then the code replaces the last underscore with a colon
+			*/
+
+			String curie = shortForm.replaceFirst("_(\\d+)$", ":$1");
 			c.properties.addProperty("shortForm", PropertyValueLiteral.fromString(shortForm));
 			c.properties.addProperty("curie", PropertyValueLiteral.fromString(curie));
 		    }
 		}
 		long endTime3 = System.nanoTime();
 		logger.info("annotate short forms: {}", ((endTime3 - startTime3) / 1000 / 1000 / 1000));
-
-
 	}
 
 	private static String extractShortForm(OntologyGraph graph, Set<String> ontologyBaseUris, String preferredPrefix,