remove commons-lang3 usage from DoubleMeanAggregatorFactoryTest (#9578)

processing/src/main/java/org/apache/druid/query/aggregation/mean/DoubleMeanHolder.java

@@ -27,6 +27,7 @@ import com.google.common.primitives.Doubles;
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.Comparator;
+import java.util.Objects;
 
 public class DoubleMeanHolder
 {
@@ -68,6 +69,26 @@ public class DoubleMeanHolder
     return buf.array();
   }
 
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    DoubleMeanHolder that = (DoubleMeanHolder) o;
+    return Double.compare(that.sum, sum) == 0 &&
+           count == that.count;
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(sum, count);
+  }
+
   public static DoubleMeanHolder fromBytes(byte[] data)
   {
     ByteBuffer buf = ByteBuffer.wrap(data);

processing/src/test/java/org/apache/druid/query/aggregation/mean/DoubleMeanAggregatorFactoryTest.java

@@ -19,7 +19,6 @@
 
 package org.apache.druid.query.aggregation.mean;
 
-import org.apache.commons.lang3.builder.EqualsBuilder;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -40,10 +39,10 @@ public class DoubleMeanAggregatorFactoryTest
     DoubleMeanHolder expectedHolder = new DoubleMeanHolder(50.0, 10L);
 
     DoubleMeanHolder actualHolder = (DoubleMeanHolder) factory.deserialize(expectedHolder);
-    Assert.assertTrue(EqualsBuilder.reflectionEquals(expectedHolder, actualHolder));
+    Assert.assertEquals(expectedHolder, actualHolder);
 
     actualHolder = (DoubleMeanHolder) factory.deserialize(expectedHolder.toBytes());
-    Assert.assertTrue(EqualsBuilder.reflectionEquals(expectedHolder, actualHolder));
+    Assert.assertEquals(expectedHolder, actualHolder);
   }
 
   @Test