title: Liquibase adding default value and not null constraint
body: <p>I am bit new to Liquibase. I came across a scenario where in one <code>changeSet</code> it is trying to add a default value first and not null constraint next to that. </p>
  
  <p>But problem over here is both <code>&lt;addDefaultValue/&gt;</code> and <code>&lt;addNotNullConstraint/&gt;</code> tags have a default value attributes so eventually I am ending up with an exception. </p>
  
  <p>Below is the <code>changeSet</code> that I have,</p>
  
  <pre><code>&lt;changeSet id="f3047816-2d48-4341-a4ce-deface083cea" author="MineStar" failOnError="true"&gt;
    &lt;preConditions onFailMessage="Ignored AlterColumn for REHANDLE of table LOCATION as column does not exist or already has a NOT NULL constraint." onFail="MARK_RAN"&gt;
      &lt;columnExists tableName="LOCATION" columnName="REHANDLE"/&gt;
      &lt;ext:columnIsNullable tableName="LOCATION" columnName="REHANDLE"/&gt;
    &lt;/preConditions&gt;
    &lt;comment&gt;AHS-1373: AlterColumn LOCATION.REHANDLE - nullability changed from true to false - defaultValue changed from 'null' to '0'&lt;/comment&gt;
    &lt;addDefaultValue columnName="REHANDLE" columnDataType="BOOLEAN" defaultValueNumeric="0" tableName="LOCATION"/&gt;
    &lt;addNotNullConstraint columnName="REHANDLE" defaultNullValue="0" columnDataType="BOOLEAN" tableName="LOCATION"/&gt;
  &lt;/changeSet&gt;
  </code></pre>
  
  <p>Here one more strange thing I could see is if I rearrange the order of adding default value and not null constraints tags I won't get any exception that is first adding not null constraint and then default value like below. But I should not do that as it effects checksum in database all that I can do is adding a new <code>changeSet</code> to resolve the exception.</p>
  
  <pre><code>&lt;addNotNullConstraint columnName="REHANDLE" defaultNullValue="0" columnDataType="BOOLEAN" tableName="LOCATION"/&gt;
  
  &lt;addDefaultValue columnName="REHANDLE" columnDataType="BOOLEAN" defaultValueNumeric="0" tableName="LOCATION"/&gt;.
  </code></pre>