liquibase-core/src/main/java/liquibase/structure/core/Relation.java
public Column getColumn(String columnName) {
        for (Column column : getColumns()) {
            if (column.getName().equalsIgnoreCase(columnName)) {
                return column;
            }
        }
        return null;
    }
public Column getColumn(String columnName) {
        for (Column column : getColumns()) {
            if (column.getName().equalsIgnoreCase(columnName)) {
                return column;
            }
        }
        return null;
    }
Returns the column object for the given columnName.  If the column does not exist in this table,
return null.