liquibase-core/src/main/java/liquibase/util/file/IOCase.java
String convertCase(String str) {
        if (str == null) {
            return null;
        }
        return isSensitive ? str : str.toLowerCase();
    }
String convertCase(String str) {
        if (str == null) {
            return null;
        }
        return isSensitive ? str : str.toLowerCase();
    }
Converts the case of the input String to a standard format.
Subsequent operations can then use standard String methods.

@param str  the string to convert, null returns null
@return the lower-case version if case-insensitive