title: How do I make a copy of java.util.Properties object?
body: <p>I have the following field and constructor:</p>
  
  <pre><code>private final Properties properties;
  
  public PropertiesExpander(Properties properties) {
      this.properties = properties;
  }
  </code></pre>
  
  <p>The good practice is to make copy of every mutable collection in constructor. I want to make a shallow, independent copy. How can I achieve that?</p>
  
  <p>My first idea was to use <code>putAll()</code> method:</p>
  
  <pre><code>private final Properties properties = new Properties();
  
  public PropertiesExpander(Properties properties) {
      this.properties.putAll(properties);
  }
  </code></pre>
  
  <p>Is there any simpler, more performant or more idiomatic way of doing that? Maybe there are some utils for that in Guava or Apache Commons?</p>