Hello,
When i add a new field to an existing class, if there is data and the field is not null i have to fix it in steps, first create the field, next update data and finally set the field to not null, However it can be fixed if its defined a default value for the new field, that should be set in the definition of the field in the database or maybe only alt liquibase level using defaultvalue.
In my case i modified the script adding defaultValue to reduce steps:
<changeSet author="mngc" id="1">
<addColumn tableName="MNGC_PERSONA">
<column name="NOMBRE_TIPO" type="VARCHAR(255)" defaultValue="COR">
<constraints nullable="false"/>
</column>
</addColumn>
</changeSet>