[DISCUSSION] How to migrate configurations from cse to servicecomb prefix

[bismy]

Hi, 


Currently we duplicate configurations for servicecomb prefix to cse prefix, and 
in code we can read configurations by cse prefix. That is:
1. Config file using servicecomb.x.y, can read in code with 
getProperty("servicecomb.x.y") and getProperty("cse.x.y")
2. Config file using cse.x.y, can read in code with getProperty("cse.x.y")


If we use cse prefix in code, this is the most portable way to read both 
cse.x.y and servicecomb.x.y configurations. 


However, this will leading us to write code always using cse, this is not our 
intention. We are asking users/developers to using servicecomb gradually.  


I suggest we use servicecomb prefix when adding new configuration items. But 
there maybe some axtra work users need to do. For example,


One user's project using cse prefix:


cse:
   function:
      a: false
      b: false


And when we add a new configuration item: servicecomb.funciton.c, users must 
change the configuration file to one of the following:


servicecomb:
  function:
     a: false
     b: false
     c: false




or 
cse:
   function:
      a: false
      b: false

servicecomb:
  function:
     c: false





I think we need to encourage users using servicecomb when upgrading, and 
developers to use servicecomb  prefix when adding new configuration items. 


Any idea?