@NotNull
@Constraint(validatedBy = OneContact.Validator.class)
@Retention(RetentionPolicy.RUNTIME)
public @interface OneContact {

    String message() default "none or more than one contact";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

    public class Validator implements ConstraintValidator<OneContact, Bean> {

        @Override
        public void initialize(final OneContact nonRecursive) {
        }

        @Override
        public boolean isValid(final Bean validationBean, final ConstraintValidatorContext constraintValidatorContext) {
            if (bean.getEmail() == null && bean.getPhone() == null) {
                return false;
            }
            return bean.getEmail() != null || bean.getPhone() != null;
        }
    }
}

@OneContact
public class Bean {

    @Email(regexp = "[a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,4}")
    private String email;

    @Pattern(regexp = "[0-9]{3,9}")
    private String phone;

    public String getEmail() {
        return email;
    }

    public void setEmail(final String email) {
        this.email = email;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(final String phone) {
        this.phone = phone;
    }
}

public void validateValidBeanParamConstraint(@Valid final Bean bean) {
     // ...
}

final ValidatorFactory validatorFactory = Validation.buildDefaultValidatorFactory();
final MethodValidator methodValidator = validatorFactory.getValidator().forMethods();

methodValidator.validateParameters(businessObject, businessMethod, new Bean());

java.lang.NullPointerException
	at org.hibernate.validator.internal.engine.MethodValidationContext.isReturnValueValidation(MethodValidationContext.java:213)
	at org.hibernate.validator.internal.engine.MethodValidationContext.createPathWithElementDescriptors(MethodValidationContext.java:130)
	at org.hibernate.validator.internal.engine.MethodValidationContext.createConstraintViolation(MethodValidationContext.java:107)
	at org.hibernate.validator.internal.engine.ValidationContext.createConstraintViolations(ValidationContext.java:250)
	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateSingleConstraint(ConstraintTree.java:293)
	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:138)
	at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:96)
	at org.hibernate.validator.internal.metadata.core.MetaConstraint.validateConstraint(MetaConstraint.java:85)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraint(ValidatorImpl.java:479)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForDefaultGroup(ValidatorImpl.java:428)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateConstraintsForCurrentGroup(ValidatorImpl.java:391)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:343)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateCascadedConstraint(ValidatorImpl.java:635)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateCascadedConstraints(ValidatorImpl.java:517)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateInContext(ValidatorImpl.java:352)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateCascadedConstraint(ValidatorImpl.java:635)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateCascadedConstraints(ValidatorImpl.java:517)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateParametersForGroup(ValidatorImpl.java:985)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateParametersInContext(ValidatorImpl.java:891)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateParameters(ValidatorImpl.java:238)
	at org.hibernate.validator.internal.engine.ValidatorImpl.validateParameters(ValidatorImpl.java:207)