improve:ProviderMethodModel add parameterClasses

[qinliujie]

What is the purpose of the change

add more information for ProviderMethodModel

Brief changelog

ProviderMethodModel add parameterClasses and genericParameterTypes property

[codecov-io]

Codecov Report

Merging #3693 into 3.x-dev will decrease coverage by 0.01%.
The diff coverage is 40%.

@@              Coverage Diff              @@
##             3.x-dev    #3693      +/-   ##
=============================================
- Coverage       63.8%   63.79%   -0.02%     
  Complexity        75       75              
=============================================
  Files            656      656              
  Lines          28449    28454       +5     
  Branches        4812     4812              
=============================================
- Hits           18152    18151       -1     
- Misses          8009     8020      +11     
+ Partials        2288     2283       -5

Impacted Files	Coverage Δ	Complexity Δ
...java/org/apache/dubbo/rpc/model/ProviderModel.java	68.57% <0%> (-2.02%)	0 <0> (ø)
...rg/apache/dubbo/rpc/model/ProviderMethodModel.java	77.27% <50%> (-6.07%)	0 <0> (ø)
...onfig/spring/extension/SpringExtensionFactory.java	70.73% <0%> (-14.64%)	0% <0%> (ø)
...ache/dubbo/remoting/transport/AbstractChannel.java	75% <0%> (-12.5%)	0% <0%> (ø)
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	77.2% <0%> (-2.21%)	0% <0%> (ø)
.../src/main/java/org/apache/dubbo/rpc/RpcStatus.java	68.13% <0%> (-2.2%)	0% <0%> (ø)
...dubbo/remoting/exchange/support/DefaultFuture.java	73.15% <0%> (-1.35%)	0% <0%> (ø)
...apache/dubbo/rpc/protocol/dubbo/DubboProtocol.java	65.25% <0%> (-0.85%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	63.04% <0%> (ø)	0% <0%> (ø)	⬇️
...rpc/protocol/dubbo/telnet/InvokeTelnetHandler.java	74.16% <0%> (+1.66%)	0% <0%> (ø)	⬇️
... and 4 more

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[ralf0131]

This may return null value, are you expecting that? Typically when you want to return a List, user will expect an empty list rather than null.