Replace 2x empty lines with a single one

src/main/java/org/apache/commons/collections4/bloomfilter/CellExtractor.java

@@ -19,7 +19,6 @@ package org.apache.commons.collections4.bloomfilter;
 import java.util.TreeMap;
 import java.util.function.IntPredicate;
 
-
 /**
  * Some Bloom filter implementations use a count rather than a bit flag. The term {@code Cell} is used to
  * refer to these counts and their associated index.  This class is the equivalent of the index extractor except

src/main/java/org/apache/commons/collections4/bloomfilter/CountingBloomFilter.java

@@ -330,7 +330,6 @@ public interface CountingBloomFilter extends BloomFilter<CountingBloomFilter>, C
         }
     }
 
-
     /**
      * Adds the specified CellExtractor to this Bloom filter.
      *

src/test/java/org/apache/commons/collections4/comparators/FixedOrderComparatorTest.java

@@ -61,7 +61,6 @@ public class FixedOrderComparatorTest extends AbstractComparatorTest<String> {
             assertFalse(comparator.equals(null));
         }
 
-
         @Test
         void expectFalseWhenFixedOrderComparatorIsComparedWithOtherObject() {
             final FixedOrderComparator<Integer> comparator = new FixedOrderComparator<>();

src/test/java/org/apache/commons/collections4/iterators/CartesianProductIteratorTest.java

@@ -31,7 +31,6 @@ import java.util.NoSuchElementException;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-
 /**
  * Test class for {@link CartesianProductIterator}.
  */

src/test/java/org/apache/commons/collections4/map/ConcurrentReferenceHashMapDefaultsTest.java

@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 
-
 package org.apache.commons.collections4.map;
 
 /**