code: public Class<?> box(Class<?> primitive) {
          if (!primitive.isPrimitive()) {
              return primitive;
          }
  
          if (int.class.equals(primitive)) {
              return Integer.class;
          } else if (long.class.equals(primitive)) {
              return Long.class;
          } else if (float.class.equals(primitive)) {
              return Float.class;
          } else if (double.class.equals(primitive)) {
              return Double.class;
          } else if (short.class.equals(primitive)) {
              return Short.class;
          } else if (boolean.class.equals(primitive)) {
              return Boolean.class;
          } else if (char.class.equals(primitive)) {
              return Character.class;
          } else if (byte.class.equals(primitive)) {
              return Byte.class;
          }
  
          throw new IllegalArgumentException("Unknown primitive type " + primitive);
      }
docs: A helper boxing method. Returns boxed class for a primitive class
  
  @param primitive
  A primitive class
  
  @return Boxed class if class was primitive, unchanged class in other cases