(cherry picked from commit d07733f1)

(cherry picked from commit 7b76b169)

(cherry picked from commit aecacce5)

Issue #2828542 by claudiu.cristea, pfrenssen, cebasqueira, heddn, alexpott: Properly check if a destination folder for a file exists

(cherry picked from commit fb17ddf0)

Issue #2746671 by Jo Fitzgerald, stella, andrewmacpherson, hussainweb, tom friedhof, chriscalip, mikeryan: CCK field data not available for D7 taxonomy term migrations

(cherry picked from commit 98350348)

Issue #2826200 by claudiu.cristea, pfrenssen: Don't let the whole migration crash on a download failure

(cherry picked from commit 08188595e5425d33460a18f31ca9c893b5d66978)

(cherry picked from commit bf02c1b1)

Issue #2827656 by maxocub, aditya.n: Once a process plugin returns multiple values, all following plugins are expected to handle multiple values

(cherry picked from commit e2d2372a00aefff8b192527861011c803a9ab251)

Revert "Issue #2746671 by Jo Fitzgerald, stella, andrewmacpherson, hussainweb, tom friedhof, chriscalip: CCK field data not available for D7 taxonomy term migrations"

This reverts commit d002382f.

Issue #2543568 by mikeryan, quietone, Ryan Weal, chipway, iMiksu, heddn, alexpott: Remove the md_entity destination plugin hack

(cherry picked from commit 09ad5fdb)

Issue #2746671 by Jo Fitzgerald, stella, andrewmacpherson, hussainweb, tom friedhof, chriscalip: CCK field data not available for D7 taxonomy term migrations

(cherry picked from commit 11cb2b73)

Issue #2767643 by maxocub, TrevorBradley, sylus, heddn, mikeryan: Scalar to array migration returns NULL

(cherry picked from commit ade5900d)

(cherry picked from commit b536f0e9)

Issue #2707387 by quietone, Adita, heddn, phenaproxima, chx: D6/7->D8 migration: Menu_links migration is not working because option parameters were not found

(cherry picked from commit d0d377cc)

Issue #2225293 by maxocub, penyaskito, Gábor Hojtsy, quietone, mitrpaka, Sonal.Sangale, rvilar, phenaproxima, Ryan Weal: Migrate D6 and D7 language negotiation settings

(cherry picked from commit 1380ab9d)

Issue #2755865 by quietone, mikeryan, alexpott, xjm: Describe Migration plugins and their relationship to source, process and destination plugins

(cherry picked from commit ed730baa)

(cherry picked from commit cbbd7217)

Issue #2825088 by kasperg: Migration property not defined in Drupal\migrate\Plugin\migrate\process\Migration

(cherry picked from commit 408f21ec)

(cherry picked from commit a772a40f)

Issue #2690001 by quietone, vasi, mikeryan, infopicard, phenaproxima: Migrate: Don't deduplicate forum vocabulary

(cherry picked from commit 5112179b)

Issue #2783715 by claudiu.cristea, chx, mikeryan, heddn, phenaproxima: Entity destination ID schema should match entity ID definition

(cherry picked from commit a4dd7f28)

Revert "Issue #2783715 by claudiu.cristea, chx, mikeryan, heddn, phenaproxima: Entity destination ID schema should match entity ID definition"

This reverts commit e29ece71.

Issue #2783715 by claudiu.cristea, chx, mikeryan, heddn, phenaproxima: Entity destination ID schema should match entity ID definition

(cherry picked from commit 3348de12)

(cherry picked from commit 0aed30b6)

Issue #2645164 by kekkis, quietone, heddn, Lars Toomre: Fix use of $sourceValues and $destinationValues local variables

(cherry picked from commit 66954069)

Issue #2778445 by neclimdul, anish.a, Charlotte17, arturs.v, iMiksu, heddn, mikeryan: Add migration message property to migrate executable

(cherry picked from commit 4471e308)

Issue #2783075 by claudiu.cristea: Followup: Add a "download" process plugin, remove remote capability from FileCopy

(cherry picked from commit 9e822c05a9dd68903050edfa01801a75aaf5c722)

Issue #2783075 by phenaproxima, claudiu.cristea, ohthehugemanatee, chx, mikeryan: Add a "download" process plugin, remove remote capability from FileCopy

(cherry picked from commit 17c15fb6)

(cherry picked from commit 20303228)

(cherry picked from commit bc7dcc91)

Issue #2818799 by claudiu.cristea: MigrateSkipRowException  being TRUE, does not skip silently as should

(cherry picked from commit 7ca0caf4)

(cherry picked from commit 16cc93d618058c45552eae09f219b55e941e50ca)

(cherry picked from commit d11cc0aa)

Issue #2801851 by shashikant_chauhan, Yogesh Pawar, phenaproxima, mikeryan: Remove system-of-record APIs from migrate

(cherry picked from commit 6416f459)

Issue #2485385 by phenaproxima, quietone, alexpott, mikeryan, Berdir, blazey, xjm, hussainweb, catch, heddn, benjy: Move highwater field support to the source plugin, and do not expose its internals on MigrationInterface

(cherry picked from commit 4259a06c)

Issue #2706405 by heddn, edysmp, davidparedes21, mikeryan, phenaproxima: File migrations *always* copy in files, even if the files were off-line copied to destination

(cherry picked from commit cb9b01246be2624188a2b0dd7e3e816220d766be)

Issue #2776235 by mikeryan, alexpott: Cached autoloader misses cause failures when missed class becomes available

(cherry picked from commit 82304ed9)

Issue #2791119 by phenaproxima, quietone, chx, mikeryan, benjy: Write meaningful Migrate source tests

(cherry picked from commit 27b61a9b)

(cherry picked from commit 2a3217ce)

Issue #2684567 by gnuget, chx, heddn, vasi, mikeryan: Requiring a migration w/ a source plugin using a generator fatals

(cherry picked from commit ae1f599d)