Proposal for deprecated o.a.d.c.extension.Activate#before and #after

[diecui1202]

I've checked the whole source code, these two methods haven't be used. Instead, #order is used more frequent.

More important, use these two properties for sorting is not correct. There has a issue and PR about it. See #1926 and #639

So, I suggest deprecating these two method on annotation Activate.

[kimmking]

+1
and I think vote should be via email？

[diecui1202]

ok. I'll send a mail for this.

[carryxyh]

+1
As far as I know, very few people use them.And this is a more edge feature

[diecui1202]

I'll send a PR to deprecate these two methods.

[cdfive]

@diecui1202
Hi, I found the ActivateComparator class use these two methods, and there is also a test case:
https://github.com/apache/incubator-dubbo/blob/master/dubbo-common/src/test/java/org/apache/dubbo/common/extension/support/ActivateComparatorTest.java
The test case use before and after method in filter's @activate， and the case is passed.

#1926 is confusing, since I tried the before,after in our project, found it works.

Consider a scene: a user's custorm filter which need to after or before a given filter, as the other filter's order are uncertain, the relative order maybe more more suitable.