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- [x] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.
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## Describe the feature
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import static org.apache.dubbo.common.constants.CommonConstants.PROVIDER;
import static org.apache.dubbo.common.constants.FilterConstants.VALIDATION_KEY;
/**
 * ValidationFilter invoke the validation by finding the right {@link Validator} instance based on the
 * configured <b>validation</b> attribute value of invoker url before the actual method invocation.
 *
 * <pre>
 *     e.g. &lt;dubbo:method name="save" validation="jvalidation" /&gt;
 *     In the above configuration a validation has been configured of type jvalidation. On invocation of method <b>save</b>
 *     dubbo will invoke {@link org.apache.dubbo.validation.support.jvalidation.JValidator}
 * </pre>
 * <p>
 * To add a new type of validation
 * <pre>
 *     e.g. &lt;dubbo:method name="save" validation="special" /&gt;
 *     where "special" is representing a validator for special character.
 * </pre>
 * <p>
 * developer needs to do
 * <br/>
 * 1)Implement a SpecialValidation.java class (package name xxx.yyy.zzz) either by implementing {@link Validation} or extending {@link org.apache.dubbo.validation.support.AbstractValidation} <br/>
 * 2)Implement a SpecialValidator.java class (package name xxx.yyy.zzz) <br/>
 * 3)Add an entry <b>special</b>=<b>xxx.yyy.zzz.SpecialValidation</b> under <b>META-INF folders org.apache.dubbo.validation.Validation file</b>.
 *
 * @see Validation
 * @see Validator
 * @see Filter
 * @see org.apache.dubbo.validation.support.AbstractValidation
 */
@Activate(group = {CONSUMER, PROVIDER}, value = VALIDATION_KEY, order = 10000)