title: Concurrent List Modification
body: <p>Below is some code (removed much of it for clarity) which shows my issue of concurrent list modification:</p>
  
  <pre><code>for (final Week week : this.demand.getWeeks().getAllWeeks()) {
      final List&lt;Week&gt; weeksExcludingThisWeek = this.demand.getWeeks().getAllWeeks();
      weeksExcludingThisWeek.remove(week);
  }
  </code></pre>
  
  <p>As far as I was aware I was removing the reference to the same week object, but in a different list than is used in the for loop. </p>
  
  <p>How do I prevent this from occurring? </p>