style(event): address PR tronprotocol#6294 review nits and assert parentHash

- Remove double blank line before parentHash field in BlockLogTrigger
- Remove trailing blank line inside toString() body
- Add testParentHashPopulated to verify capsule constructor sets parentHash

Author: clarkchen

common/src/main/java/org/tron/common/logsfilter/trigger/BlockLogTrigger.java

@@ -27,7 +27,6 @@ public class BlockLogTrigger extends Trigger {
   @Setter
   private List<String> transactionList = new ArrayList<>();
 
-
   @Getter
   @Setter
   private String parentHash;
@@ -54,6 +53,5 @@ public String toString() {
         .append(", parentHash: ")
         .append(parentHash)
         .toString();
-
   }
 }

framework/src/test/java/org/tron/common/logsfilter/capsule/BlockLogTriggerCapsuleTest.java

@@ -32,4 +32,10 @@ public void testSetLatestSolidifiedBlockNumber() {
     Assert.assertEquals(100,
         blockLogTriggerCapsule.getBlockLogTrigger().getLatestSolidifiedBlockNumber());
   }
+
+  @Test
+  public void testParentHashPopulated() {
+    Assert.assertEquals(Sha256Hash.ZERO_HASH.toString(),
+        blockLogTriggerCapsule.getBlockLogTrigger().getParentHash());
+  }
 }