feat: specify callback ip in config.json

[seeflood]

Signed-off-by: seeflood [email protected]

What this PR does:

• Specify callback ip in config.json:
  

• Run pubsub quickstart with Java sdk

Which issue(s) this PR fixes:

Fixes #684

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov]

Codecov Report

Merging #685 (aae4147) into main (97aedf9) will increase coverage by 0.02%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##             main     #685      +/-   ##
==========================================
+ Coverage   60.93%   60.95%   +0.02%     
==========================================
  Files         120      120              
  Lines        6384     6388       +4     
==========================================
+ Hits         3890     3894       +4     
  Misses       2121     2121              
  Partials      373      373              

Impacted Files	Coverage Δ
pkg/runtime/config.go	60.00% <ø> (ø)
pkg/runtime/runtime.go	60.96% <83.33%> (+0.47%)	⬆️

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