fix: website build failed

immutable/README.md

@@ -33,10 +33,6 @@ Wikipedia says
 
 > In object-oriented and functional programming, an immutable object (unchangeable object) is an object whose state cannot be modified after it is created. This is in contrast to a mutable object (changeable object), which can be modified after it is created.
 
-Class diagram
-
-![Immutable class diagram](./etc/immutable.urm.puml)
-
 ## Programmatic Example of Immutable Pattern in Java
 
 The core of the pattern is `ImmutableUser`. All fields are `final`, the mutable `roles` list is defensively copied via `List.copyOf`, and "mutation" is expressed by returning a new instance.

immutable/etc/immutable.urm.puml

@@ -1,21 +0,0 @@
-@startuml
-package com.iluwatar.immutable {
-  class App {
-    - LOGGER : Logger {static}
-    + App()
-    + main(args : String[]) {static}
-  }
-  class ImmutableUser {
-    - name : String {final}
-    - age : int {final}
-    - roles : List<String> {final}
-    + ImmutableUser(name : String, age : int, roles : List<String>)
-    + getName() : String
-    + getAge() : int
-    + getRoles() : List<String>
-    + withAge(newAge : int) : ImmutableUser
-    + toString() : String
-  }
-}
-App ..> ImmutableUser : creates
-@enduml