Remove unnecessary check

Author: spaske00

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/image/NativeImageHeap.java

@@ -905,29 +905,21 @@ enum HeapInclusionReason {
     }
 
     final class ObjectReachabilityInfo {
-        private final Object firstReason;
-        private LinkedHashSet<Object> allReasons;
+        private final LinkedHashSet<Object> allReasons;
         private int objectReachabilityGroup;
 
         ObjectReachabilityInfo(ObjectInfo info, Object firstReason) {
-            this.firstReason = firstReason;
-            this.allReasons = null;
+            this.allReasons = new LinkedHashSet<>();
+            this.allReasons.add(firstReason);
             this.objectReachabilityGroup = ObjectReachabilityGroup.getFlagForObjectInfo(info, firstReason, objectReachabilityInfo);
         }
 
         void addReason(Object additionalReason) {
-            if (allReasons == null) {
-                this.allReasons = new LinkedHashSet<>();
-            }
             this.allReasons.add(additionalReason);
             this.objectReachabilityGroup |= ObjectReachabilityGroup.getByReason(additionalReason, objectReachabilityInfo);
         }
 
         Set<Object> getAllReasons() {
-            if (allReasons == null) {
-                this.allReasons = new LinkedHashSet<>();
-            }
-            this.allReasons.add(firstReason);
             return this.allReasons;
         }