Fixed memory leak in SpanStore

SpanStore implementation was causing a slow memory leak by not releasing map entries (#42)

Full Changelog: v1.19.0...v1.21.1

Update to newer Java agent version and fixes

• Update the agent to Java APM agent 1.19.0
• Fix for crash on DevKit steps not implementing AnnotatedObject #39
• Turning the lambda into explicit anonymous class and surrounding with try/catch - opportunistic fix for #40

Support for Java APM agent 1.17.0

Support for Java APM agent 1.17.0

Support for Java APM agent 1.16.0

Support for Java APM agent 1.16.0
Fix for #28 in 3.8.x and 3.9.x

Support for log correlation

Now transaction.id and trace.id are populated in the MDC contextMap similar to the default Java APM agent behaviour:
https://www.elastic.co/guide/en/apm/agent/java/current/log-correlation.html

Support for Elastic Java APM agent v1.15.0

Updated to Elastic APM agent to v1.15.0
Updated to ByteBuddy 1.10.8
Updated README instructions
Downgraded 3.8 clients to support Mule EE 3.8.0 to support later Mule 3.8 versions

• Support for JMX metrics through newer APM agent

Support for Mule 3.9.3 and APM Java agent 1.8.0

This release supports Mule 3.9.3, as there was a defect with v1.7.0. It also adds support for the latest v1.8.0 Elastic Java APM agent. For more details on the new features (including BETA centralised agent management) see https://github.com/elastic/apm-agent-java/releases/tag/v1.8.0

Support for APM agent v1.7.0

This release updates Elastic APM agent to version 1.7.0 and fixes initialisation error in domain-tracer.xml

Support for Java agent v1.6.1 + Mule 3.8 support

• Support for Java agent v1.6.1
• Separate jar for Mule 3.8 projects

Reworked error handling

Reworked error handling