code: public static InputStream getResourceAsStream(String name, Class<?> cls)
              throws IOException {
          if (cls == null) {
              cls = IOUtil.class;
          }
          if (name == null) {
              throw new IllegalArgumentException("resource cannot be null");
          }
          InputStream result = cls.getResourceAsStream(name);
          if (result == null) {
              throw new IOException("Could not open resource " + name
                      + " using " + cls.getName() + "'s class loader");
          }
          return result;
      }
docs: Finds a resource with a given name using the class loader of the
  specified class. Functions identically to
  {@link Class#getResourceAsStream(java.lang.String)}, except it throws an
  {@link IllegalArgumentException} if the specified resource name is
  <code>null</code>, and it throws an {@link IOException} if no resource
  with the specified name is found.
  
  @param name name {@link String} of the desired resource. Cannot be
  <code>null</code>.
  @param cls the {@link Class} whose loader to use.
  @return an {@link InputStream}.
  @throws IOException if no resource with this name is found.