* @since 4.0.0
 */
@Experimental
public interface VersionConstraint {
    /**
     * Returns the range of this constraint, or {@code null} if none.
     * <p>
     * Note: only one, this method or {@link #getRecommendedVersion()} method must return non-{@code null} value.
     */
    @Nullable
    VersionRange getVersionRange();

    /**
     * Returns the recommended version of this constraint, or {@code null} if none.
     * <p>

        VersionConstraint c = versionParser.parseVersionConstraint("1.0");
        assertEquals("1.0", c.getRecommendedVersion().toString());
        assertTrue(c.contains(versionParser.parseVersion("1.0")));

        c = versionParser.parseVersionConstraint("[1.0]");
        assertNull(c.getRecommendedVersion());
        assertTrue(c.contains(versionParser.parseVersion("1.0")));

                return null;
            }
            return new DefaultVersionRange(versionScheme, delegate.getRange());
        }

        @Override
        public Version getRecommendedVersion() {
            if (delegate.getVersion() == null) {
                return null;
            }
            return new DefaultVersion(versionScheme, delegate.getVersion());
        }

        @Override