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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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package java.security;

import javax.security.auth.Subject;

/**
 * This interface represents the abstract notion of a principal, which
 * can be used to represent any entity, such as an individual, a
 * corporation, and a login id.
 *
 * @see java.security.cert.X509Certificate
 *
 * @author Li Gong
 * @since 1.1
 */
public interface Principal {

    /**
     * Compares this principal to the specified object.  Returns true
     * if the object passed in matches the principal represented by
     * the implementation of this interface.
     *
     * @param another principal to compare with.
     *
     * @return true if the principal passed in is the same as that
     * encapsulated by this principal, and false otherwise.
     */
    public boolean equals(Object another);

    /**
     * Returns a string representation of this principal.
     *
     * @return a string representation of this principal.
     */
    public String toString();

    /**
     * Returns a hashcode for this principal.
     *
     * @return a hashcode for this principal.
     */
    public int hashCode();

    /**
     * Returns the name of this principal.
     *
     * @return the name of this principal.
     */
    public String getName();

    /**
     * Returns true if the specified subject is implied by this principal.
     *
     * @implSpec
     * The default implementation of this method returns true if
     * {@code subject} is non-null and contains at least one principal that
     * is equal to this principal.
     *
     * <p>Subclasses may override this with a different implementation, if
     * necessary.
     *
     * @param subject the {@code Subject}
     * @return true if {@code subject} is non-null and is
     *              implied by this principal, or false otherwise.
     * @since 1.8
     */
    public default boolean implies(Subject subject) {
        if (subject == null)
            return false;
        return subject.getPrincipals().contains(this);
    }
}