package org.killbill.billing.catalog.api;

public interface Usage {

    /**
     *
     * @return  @return the {@code BillingPeriod}
     */
    public BillingPeriod getBillingPeriod();

    /**
     * @return compliance boolean
     */
    public boolean compliesWithLimits(String unit, double value);

}

package org.killbill.billing.catalog.api;

public interface Usage {

    /**
     *
     * @return  @return the {@code BillingPeriod}
     */
    public BillingPeriod getBillingPeriod();

    /**
     * @return compliance boolean
     */
    public boolean compliesWithLimits(String unit, double value);

    /**
     *
     * @return the {@code Limit} associated with that usage section
     */
    public Limit[] getLimits();
}

Add limits to Usage section