[fix][fn] Make /version return correct version

[michaeljmarshall]

Motivation

The /version endpoint for functions currently returns {"version":"version.number"} instead of an actual version number. This PR fixes that.

One observation is that the broker's /version endpoint returns a plain string:

pulsar/pulsar-broker/src/main/java/org/apache/pulsar/broker/admin/impl/BrokersBase.java

Lines 527 to 535 in 82237d3

	@GET
	@Path("/version")
	@ApiOperation(value = "Get version of current broker")
	@ApiResponses(value = {
	@ApiResponse(code = 200, message = "Everything is OK"),
	@ApiResponse(code = 500, message = "Internal server error")})
	public String version() throws Exception {
	return PulsarVersion.getVersion();
	}

Modifications

• Return the actual version.
• Use a static field to decrease the cost of this endpoint.

Verifying this change

This is a trivial change.

Documentation

• doc-not-needed

This fixes an endpoint, no docs are needed.

Matching PR in forked repository

PR in forked repository: Skipping PR since this is so trivial

[codecov-commenter]

Codecov Report

Merging #20047 (b28f95c) into master (3b118b6) will increase coverage by 0.05%.
The diff coverage is 44.39%.

@@             Coverage Diff              @@
##             master   #20047      +/-   ##
============================================
+ Coverage     72.86%   72.91%   +0.05%     
- Complexity    31628    31649      +21     
============================================
  Files          1861     1858       -3     
  Lines        137500   137420      -80     
  Branches      15141    15107      -34     
============================================
+ Hits         100187   100203      +16     
+ Misses        29351    29236     -115     
- Partials       7962     7981      +19     

Flag	Coverage Δ
inttests	24.42% <0.95%> (+0.02%)	⬆️
systests	25.01% <20.04%> (-0.01%)	⬇️
unittests	72.18% <35.32%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...a/org/apache/pulsar/broker/admin/v2/Functions.java	0.00% <0.00%> (ø)
...java/org/apache/pulsar/broker/admin/v2/Worker.java	11.76% <0.00%> (ø)
...org/apache/pulsar/broker/admin/v2/WorkerStats.java	40.00% <0.00%> (ø)
...r/functions/worker/rest/ConfigurationResource.java	0.00% <0.00%> (ø)
...ons/worker/rest/api/v2/FunctionsApiV2Resource.java	0.00% <0.00%> (ø)
...s/worker/rest/api/v2/WorkerStatsApiV2Resource.java	0.00% <0.00%> (ø)
...ulsar/functions/worker/rest/api/FunctionsImpl.java	56.55% <16.66%> (-0.74%)	⬇️
...org/apache/pulsar/broker/admin/impl/SinksBase.java	35.29% <35.71%> (ø)
...g/apache/pulsar/broker/admin/impl/SourcesBase.java	35.29% <35.71%> (-1.85%)	⬇️
...ons/worker/rest/api/v3/FunctionsApiV3Resource.java	43.39% <37.50%> (ø)
... and 16 more

... and 63 files with indirect coverage changes