liquibase-core/src/main/java/liquibase/change/ColumnConfig.java
public ColumnConfig setValueBoolean(String valueBoolean) {
        valueBoolean = StringUtil.trimToNull(valueBoolean);
        if ((valueBoolean == null) || "null".equalsIgnoreCase(valueBoolean)) {
            this.valueBoolean = null;
        } else {
            if ("true".equalsIgnoreCase(valueBoolean) || "1".equals(valueBoolean)) {
                this.valueBoolean = true;
            } else if ("false".equalsIgnoreCase(valueBoolean) || "0".equals(valueBoolean)) {
                this.valueBoolean = false;
            } else {
                this.valueComputed = new DatabaseFunction(valueBoolean);
            }

        }

        return this;
    }
public ColumnConfig setValueBoolean(String valueBoolean) {
        valueBoolean = StringUtil.trimToNull(valueBoolean);
        if ((valueBoolean == null) || "null".equalsIgnoreCase(valueBoolean)) {
            this.valueBoolean = null;
        } else {
            if ("true".equalsIgnoreCase(valueBoolean) || "1".equals(valueBoolean)) {
                this.valueBoolean = true;
            } else if ("false".equalsIgnoreCase(valueBoolean) || "0".equals(valueBoolean)) {
                this.valueBoolean = false;
            } else {
                this.valueComputed = new DatabaseFunction(valueBoolean);
            }

        }

        return this;
    }
Set the valueBoolean based on a given string.
If the passed value cannot be parsed as a date, it is assumed to be a function that returns a boolean.
If the string "null" or an empty string is passed, it will set a null value.
If "1" is passed, defaultValueBoolean is set to true. If 0 is passed, defaultValueBoolean is set to false