Starting 's'(s) are dropped from custom message field names

[sobhanebr]

I was using http sink plugin and I had a 'startInterval' property in my custom message. Running the pipeline was failed because of throwing Field tartInterval doesnt exist in the input schema. exception. I checked the Matcher and found out it would consider field names with starting 's's dropped. Maybe there are some better regex to use.

http/src/main/java/io/cdap/plugin/http/sink/batch/HTTPSink.java

Line 68 in 7eb1b8e

private static final String REGEX_HASHED_VAR = "#s*(\\w+)";