liquibase-core/src/main/java/liquibase/util/NumberUtils.java
public static Integer readInteger(String value) {
        if (value == null) {
            return null;
        }
        return Integer.valueOf(value);
    }
public static Integer readInteger(String value) {
        if (value == null) {
            return null;
        }
        return Integer.valueOf(value);
    }
Convenience method for converting a string to an Integer object
@param value string value
@return Null if the value is null, otherwise the converted integer