This PR accumulates many refactorings and small improvements that I did while preparing the next change set of https://github.com/druid-io/druid/projects/2. I finally decided to make them a separate PR to minimize the volume of the main PR.
Some of the changes:
- Renamed confusing "Generic Column" term to "Numeric Column" (what it actually implies) in many class names.
- Generified `ComplexMetricExtractor`
* Adding licenses and enable apache-rat-plugi.
Change-Id: I4685a2d9f1e147855dba69329b286f2d5bee3c18
* restore the copywrite of demo_table and add it to the list of allowed ones
Change-Id: I2a9efde6f4b984bc1ac90483e90d98e71f818a14
* revirew comments
Change-Id: I0256c930b7f9a5bb09b44b5e7a149e6ec48cb0ca
* more fixup
Change-Id: I1355e8a2549e76cd44487abec142be79bec59de2
* align
Change-Id: I70bc47ecb577bdf6b91639dd91b6f5642aa6b02f
* Rename io.druid to org.apache.druid.
* Fix META-INF files and remove some benchmark results.
* MonitorsConfig update for metrics package migration.
* Reorder some dimensions in inner queries for some reason.
* Fix protobuf tests.