code: public MethodInvocation on(Object target) {
      Assert.isTrue(target != null || ModifierUtils.isStatic(getMethod()),
        "Method must be static if target is null");
  
      this.target = target;
  
      return this;
    }
docs: Sets the target {@link Object} on which the {@link Method} will be invoked.
  
  @param target {@link Object} on which the {@link Method} will be invoked.
  @return this {@link MethodInvocation}.
  @throws IllegalArgumentException if {@link Object target} is {@literal null} and {@link Method}
  is not {@link java.lang.reflect.Modifier#STATIC}.
  @see org.cp.elements.lang.reflect.MethodInvocation
  @see java.lang.Object
  @see #getMethod()