add paper reference to original source to pattern entity (#33)

Author: manuwei

src/main/java/io/github/patternatlas/api/entities/Pattern.java

@@ -26,6 +26,8 @@ public class Pattern extends EntityWithURI {
 
     private String iconUrl;
 
+    private String paperRef;
+
     @JsonIgnore
     @ToString.Exclude
     @ManyToOne

src/main/java/io/github/patternatlas/api/rest/controller/PatternController.java

@@ -36,16 +36,16 @@
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 
-import io.github.patternatlas.api.exception.DirectedEdgeNotFoundException;
-import io.github.patternatlas.api.exception.UndirectedEdgeNotFoundException;
-import io.github.patternatlas.api.rest.model.PatternRenderedContentModel;
 import io.github.patternatlas.api.entities.DirectedEdge;
 import io.github.patternatlas.api.entities.Pattern;
 import io.github.patternatlas.api.entities.PatternLanguage;
 import io.github.patternatlas.api.entities.PatternViewPattern;
 import io.github.patternatlas.api.entities.UndirectedEdge;
+import io.github.patternatlas.api.exception.DirectedEdgeNotFoundException;
+import io.github.patternatlas.api.exception.UndirectedEdgeNotFoundException;
 import io.github.patternatlas.api.rest.model.PatternContentModel;
 import io.github.patternatlas.api.rest.model.PatternModel;
+import io.github.patternatlas.api.rest.model.PatternRenderedContentModel;
 import io.github.patternatlas.api.service.PatternLanguageService;
 import io.github.patternatlas.api.service.PatternRelationDescriptorService;
 import io.github.patternatlas.api.service.PatternRenderService;
@@ -402,6 +402,7 @@ EntityModel<Pattern> updatePatternViaPut(@PathVariable UUID patternLanguageId, @
             persistedVersion.setRenderedContent(pattern.getContent());
         }
         persistedVersion.setIconUrl(pattern.getIconUrl());
+        persistedVersion.setPaperRef(pattern.getPaperRef());
         persistedVersion.setContent(pattern.getContent());
         persistedVersion.setName(pattern.getName());