remove sumMod2 method

since its equivalent is just countOnes() % 2, which has the exact same complexity and implementation

Author: geompokon@csd.auth.gr

src/main/java/io/github/abductcows/bitarray/BitArray.java

@@ -532,30 +532,6 @@ private int longsRequiredForNBits(int nBits) {
         BitArray specific methods
     */
 
-    /**
-     * Calculates the parity of {@link Boolean#TRUE ones} in the array
-     *
-     * @return 0 or 1 if there is an even or odd number of {@link Boolean#TRUE ones} respectively
-     */
-    public int sumMod2() {
-        if (isEmpty()) return 0;
-        int sumMod2 = 0;
-        int limit = longsRequiredForNBits(size()) - 1;
-
-        sumMod2 += Long.bitCount(Arrays.stream(data)
-                .limit(limit)
-                .reduce(0L, (i, j) -> i ^ j));
-
-        int remainingBitsIndex = limit * BITS_PER_LONG;
-        for (int i = remainingBitsIndex; i < elements; i++) {
-            if (get(i)) {
-                sumMod2++;
-            }
-        }
-
-        return sumMod2 % 2;
-    }
-
     /**
      * Counts the number of {@code true} elements in the array
      *

src/test/kotlin/io/github/abductcows/bitarray/BitArrayTest.kt

@@ -191,22 +191,6 @@ internal class BitArrayTest {
     @DisplayName("New Method Tests")
     @TestInstance(TestInstance.Lifecycle.PER_CLASS)
     internal inner class NewMethodTests {
-        @ParameterizedTest(name = "{0} elements")
-        @MethodSource("io.github.abductcows.bitarray.TestUtils#testCaseBooleans")
-        @DisplayName("sumMod2 is equivalent to parity of 1s in the array")
-        fun `sumMod2 should be equivalent to the parity of 1s in the array`(elementsToAdd: List<Boolean>) {
-            // given
-            bitArray.addAll(elementsToAdd)
-
-            // when
-            val sumMod2 = bitArray.sumMod2()
-            val expectedSumMod2 = bitArray.count { it == true } % 2
-
-            // then
-            printDetails(elementsToAdd.size, expectedSumMod2, sumMod2)
-            assertThat(sumMod2).isEqualTo(expectedSumMod2)
-        }
-
         @ParameterizedTest(name = "{0} elements")
         @MethodSource("io.github.abductcows.bitarray.TestUtils#testCaseBooleans")
         @DisplayName("countOnes is equivalent to the number of true elements in the array")