Optimize code to remove useless objects

[srchen1987]

Optimize code to remove useless objects

update before
public void addAttachments(Map<String, String> attachments) {
if (attachments == null) {
return;
}
if (this.attachments == null) {
this.attachments = new HashMap<String, String>();
}
this.attachments.putAll(attachments);
}

update after
public void addAttachments(Map<String, String> attachments) {
if (attachments == null) {
return;
}
if (this.attachments == null) {
this.attachments = attachments;
}else{
this.attachments.putAll(attachments);
}
}

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@3e02287). Click here to learn what that means.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##             master    #7582   +/-   ##
=========================================
  Coverage          ?   59.01%           
  Complexity        ?      527           
=========================================
  Files             ?     1076           
  Lines             ?    43417           
  Branches          ?     6339           
=========================================
  Hits              ?    25621           
  Misses            ?    14951           
  Partials          ?     2845           

Impacted Files	Coverage Δ	Complexity Δ
...main/java/com/alibaba/dubbo/rpc/RpcInvocation.java	0.00% <0.00%> (ø)	0.00 <0.00> (?)

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[kevinw66]

duplicate with #7572

[srchen1987]

duplicate with #7572

Deadlock? That version because I wrote comments, this version removed the comments. The previous code is meaningless and will not be submitted any more