fix: Use concise Pact Source descriptions

[asteffey]

Problem to solve

Pact provider tests print out overly verbose Pact source descriptions (i.e. use default Kotlin toString) when using a Directory or Pact Broker source.

Steps to reproduce

Seen when running provider tests using Pacts from a directory or Pact-Broker with pact-jvm-provider-junit5 plugin.

Current behavior

Verifying a pact between JsonConsumer and JsonProvider
  [Using DirectorySource(dir=target\pacts, pacts={target\pacts\JsonConsumer-JsonProvider.json=MessagePact(provider=Provider(name=JsonProvider), consumer=Consumer(name=JsonConsumer), messages=[Message(description='json array with extra values', providerStates=[ProviderState(name=some state, params={})], contents=PRESENT({"JsonArray":[{"key":"required"},{"key":"something else"}]}), matchingRules=MatchingRules(rules={body=Category(name=body, matchingRules={$.JsonArray=MatchingRuleGroup(rules=[MinTypeMatcher(min=1)], ruleLogic=AND), $.JsonArray[*].key=MatchingRuleGroup(rules=[au.com.dius.pact.core.model.matchingrules.TypeMatcher@6c0d7c83], ruleLogic=AND)})}), generators=Generators(categories={}), metaData={contentType=application/json; charset=UTF-8}), Message(description='json object with extra values', providerStates=[ProviderState(name=some state, params={})], contents=PRESENT({"JsonObject":{"key":"required"}}), matchingRules=MatchingRules(rules={body=Category(name=body, matchingRules={$.JsonObject.key=MatchingRuleGroup(rules=[au.com.dius.pact.core.model.matchingrules.TypeMatcher@6c0d7c83], ruleLogic=AND)})}), generators=Generators(categories={}), metaData={contentType=application/json; charset=UTF-8})], metadata={pactSpecification={version=3.0.0}, pact-jvm={version=4.0.1}})})]
  Given some state
  json array with extra values
    generates a message which
      has a matching body (OK)
      has matching metadata (OK)

Expected behavior

Verifying a pact between JsonConsumer and JsonProvider
  [Using Directory target\pacts]
  Given some state
  json array with extra values
    generates a message which
      has a matching body (OK)
      has matching metadata (OK)

Proposed Fix

Implement description methods for DirectorySource and PactBrokerSource,
instead of having them fallback to default Kotlin toString.

Have PactBrokerLoader resolve system parameters, so PactBrokerSource
shows a valid url instead of ${...} placeholders.

NOTICE

This software was produced for the U. S. Government under Contract No. FA8702-20-C-0001, and is subject to the Rights in Noncommercial Computer Software and Noncommercial Computer Software Documentation Clause DFARS 252.227-7014 (FEB 2014)

Approved for Public Release; Distribution Unlimited. Case Number 19-3203.

(c) 2020 The MITRE Corporation. All Rights Reserved.

[asteffey]

in the latest revision, I applied the same changes to the new kotlin version of PactBrokerLoader instead.

[uglyog]

4.0.6 has been released with this fix