学习代码，java包应用

Map<String, String> () {
Collections.emptyMap();
}

Objects.requireNonNull(other);
public void initializeBuilder(Log4jLogEvent.Builder builder) {
builder.setContextMap(contextMap) //
.setContextStack(contextStack) //
public Builder setContextStack(ThreadContext.ContextStack contextStack) {
this.contextStack = contextStack;
return this;
}

Map<String, String> () {
Collections.emptyMap();
}

Map<String, String> () {
Collections.emptyMap();
}

Map<String, String> () {
Collections.emptyMap();
}Map<String, String> () {
Collections.emptyMap();
}