rewrite MethodJoin and add test

[robfrank]

What does this PR do?

Add test for the the new SqlMethodJoin

Motivation

The new merged method here #1584 missed test and documentation

This adds tests and rewrites the code using idiomatic Java streams and joiners

Checklist

• I have run the build using mvn clean package command
• My unit tests cover both failure and success scenarios

[lvca]

thanks @robfrank !!!

[gramian]

From me too: thanks @robfrank !

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for 2b711751	✅ 0.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (2b71175)	Report Missing	Report Missing	Report Missing
Head commit (21ecc49)	64921	0	0.00%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#1585)	14	0	0.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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Footnotes

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