Added: primary in IndexSettings

Fix: #581

Author: Ant-hem

algoliasearch-core/src/main/java/com/algolia/search/models/settings/IndexSettings.java

@@ -33,6 +33,7 @@ public class IndexSettings implements Serializable {
   private List<String> attributesToRetrieve;
   private List<String> camelCaseAttributes;
   private Map<String, List<String>> decompoundedAttributes;
+  private String primary;
 
   /* filtering-faceting */
   private Long maxValuesPerFacet;
@@ -234,6 +235,10 @@ public IndexSettings setDecompoundedAttributes(Map<String, List<String>> decompo
     return this;
   }
 
+  public String getPrimary() {
+    return primary;
+  }
+
   public List<String> getAttributesToHighlight() {
     return attributesToHighlight;
   }