Fix test method name and visibility

Author: garydgregory

src/test/java/org/apache/commons/lang3/math/NumberUtilsTest.java

@@ -1262,7 +1262,7 @@ void testLang381() {
     }
 
     @Test
-    public void TestLang747() {
+    void testLang747() {
         assertEquals(Integer.valueOf(0x8000), NumberUtils.createNumber("0x8000"));
         assertEquals(Integer.valueOf(0x80000), NumberUtils.createNumber("0x80000"));
         assertEquals(Integer.valueOf(0x800000), NumberUtils.createNumber("0x800000"));