fix pointer value set

[tiltwind]

What this PR does:
From v1.12.0, hessian starts to support pointer value ref to java wrapper types, but the unit tests does not fully cover all cases. This pr fixes the pointer value set.

Which issue(s) this PR fixes:

Fixes #358

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

- fix pointer value set

[codecov-commenter]

Codecov Report

Merging #361 (1dc8c16) into master (7231dc5) will increase coverage by 0.37%.
The diff coverage is 77.46%.

❗ Current head 1dc8c16 differs from pull request most recent head f9c7f78. Consider uploading reports for the commit f9c7f78 to get more accurate results

@@            Coverage Diff             @@
##           master     #361      +/-   ##
==========================================
+ Coverage   68.60%   68.98%   +0.37%     
==========================================
  Files          28       28              
  Lines        3217     3140      -77     
==========================================
- Hits         2207     2166      -41     
+ Misses        775      751      -24     
+ Partials      235      223      -12     

Impacted Files	Coverage Δ
java_lang.go	100.00% <ø> (ø)
object.go	72.93% <0.00%> (+3.30%)	⬆️
ref.go	83.11% <ø> (ø)
decode.go	69.82% <73.91%> (+0.64%)	⬆️
codec.go	70.43% <82.22%> (+5.21%)	⬆️
list.go	86.34% <100.00%> (ø)

... and 5 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[alpha-baby]

good

[wongoo]

dubbo-go integration test , ref apache/dubbo-go#2312