liquibase-core/src/main/java/liquibase/sql/visitor/SqlVisitorFactory.java
public SqlVisitor create(String tagName) {
        Class<?> aClass = tagToClassMap.get(tagName);
        if (aClass == null) {
            return null;
        }
        try {
            return (SqlVisitor) aClass.getConstructor().newInstance();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
public SqlVisitor create(String tagName) {
        Class<?> aClass = tagToClassMap.get(tagName);
        if (aClass == null) {
            return null;
        }
        try {
            return (SqlVisitor) aClass.getConstructor().newInstance();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
Create a new Change subclass based on the given tag name.