title: Liquibase set column default value to null
body: <p>I tried with liquibase to set the default value of my column to null with liquibase "addDefaultValue" syntax:</p>
  
  <pre><code>&lt;changeSet id="20181213171501-2"&gt;
      &lt;!-- Add default value --&gt;
      &lt;addDefaultValue tableName="myTable"
          columnDataType="boolean"
          columnName="myColumn"
          defaultValueBoolean="null" /&gt;
  &lt;/changeSet&gt;
  </code></pre>
  
  <p>But inserting a new row to myTable showed that the default value was still set to 'false', as before. So liquibase changeset didn't work.</p>
  
  <p>How to set a column default value to null with liquibase?</p>