public static String capitalize(String str) {
        return changeFirstCharacterCase(str);
    }
@Test
    void testCapitalize() {
        // Test for an empty string
        String str1 = "";
        assertEquals("", StringUtils.capitalize(str1));
        
        // Test for a single word string
        String str2 = "hello";
        assertEquals("Hello", StringUtils.capitalize(str2));
        
        // Test for a multiple word string
        String str3 = "hello world";
        assertEquals("Hello world", StringUtils.capitalize(str3));
        
        // Test for a string with special characters
        String str4 = "!@#$%^&*()";
        assertEquals("!@#$%^&*()", StringUtils.capitalize(str4));
        
        // Test for a string with numbers
        String str5 = "abc123";
        assertEquals("Abc123", StringUtils.capitalize(str5));
    }