This reverts commit 7c486399.

Issue #2839951 by chiranjeeb2410, badjava: API docs FormattableMarkup::placeholderFormat %variable example contain errors

Issue #2807705 by alexpott, dawehner, aburke626: FormattableMarkup::placeholderFormat() can result in unsafe replacements

Revert "Issue #2807705 by alexpott, dawehner, aburke626: FormattableMarkup::placeholderFormat() can result in unsafe replacements"

This reverts commit 8477ed5a.

Issue #2807705 by alexpott, dawehner, aburke626: FormattableMarkup::placeholderFormat() can result in unsafe replacements

Issue #2711537 by chgasparoto, kostyashupenko: Syntax errors (un-quoted or mis-quoted strings) in various code examples in docs

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2337283 by hussainweb, Mile23, alexpott, aleksip, dawehner, heykarthikwithu, naveenvalecha, Crell, xjm, davidwbarratt, Fabianx, jhedstrom, tim.plunkett, larowlan, tstoeckler: Add a composer.json file to every component

Issue #2579691 by lauriii, alexpott, stefan.r, YesCT, dawehner: Remove usages of SafeMarkup::isSafe()

Issue #2608054 by stefan.r: Give more context in invalid placeholder error message PlaceholderTrait::placeholderFormat()

Issue #2600672 by alexpott, dawehner: Core MarkupInterface implementations used in Twig templates should implement \Countable

Issue #2575703 by borisson_, stefan.r, Berdir, joshi.rohit100: Remove default fall-through from PlaceholderTrait::placeholderFormat()

Issue #2575615 by alexpott, pwolanin, stefan.r, catch, dawehner, effulgentsia, xjm, David_Rothstein, iMiksu, lauriii, joelpittet: Introduce HtmlEscapedText and remove SafeMarkup::setMultiple() and SafeMarkup::getAll() and remove the static safeStrings list

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes