[util-core, inject-utils]: Move c.t.inject.conversions.seq to util-core

Problem

Finatra's inject-utils/conversions contains useful seq conversion methods that
would fit better in util-core/conversions.

Solution

Deprecate everything in `c.t.inject.conversions.seq`, and move the
functionality to util-core, along with the corresponding tests.

JIRA Issues: CSL-10371

Differential Revision: https://phabricator.twitter.biz/D578605

CHANGELOG.rst

@@ -15,6 +15,9 @@ Added
 Changed
 ~~~~~~~
 
+* inject-utils: Deprecate all methods in `c.t.inject.conversions.seq`, and move functionality
+  to `c.t.conversions.SeqOps` in the util/util-core project.. ``PHAB_ID=D578605``
+
 * inject-utils: Remove deprecated `camelify`, `pascalify`, and `snakify` from
   `c.t.inject.conversions.string.RichString`. Additionally, deprecate `toOption` and
   `getOrElse` in `c.t.inject.conversions.string.RichString`, and move functionality to

inject/inject-utils/src/main/scala/com/twitter/inject/conversions/seq.scala

@@ -1,47 +1,31 @@
 package com.twitter.inject.conversions
 
-import scala.annotation.tailrec
+import com.twitter.conversions.SeqOps
 
+@deprecated("Use com.twitter.conversions.SeqOps instead", "2020-11-16")
 object seq {
 
   implicit class RichSeq[A](val self: Seq[A]) extends AnyVal {
 
-    def createMap[K, V](keys: A => K, values: A => V): Map[K, V] = {
-      self.iterator.map { elem =>
-        keys(elem) -> values(elem)
-      }.toMap
-    }
+    @deprecated("Use com.twitter.conversions.SeqOps#createMap instead", "2020-11-16")
+    def createMap[K, V](keys: A => K, values: A => V): Map[K, V] =
+      SeqOps.createMap(self, keys, values)
 
-    def createMap[K, V](values: A => V): Map[A, V] = {
-      self.iterator.map { elem =>
-        elem -> values(elem)
-      }.toMap
-    }
+    @deprecated("Use com.twitter.conversions.SeqOps#createMap instead", "2020-11-16")
+    def createMap[K, V](values: A => V): Map[A, V] = SeqOps.createMap(self, values)
 
-    def foreachPartial(pf: PartialFunction[A, Unit]): Unit = {
-
-      self.foreach { elem =>
-        if (pf.isDefinedAt(elem)) {
-          pf(elem)
-        }
-      }
-    }
+    @deprecated("Use com.twitter.conversions.SeqOps#foreachPartial instead", "2020-11-16")
+    def foreachPartial(pf: PartialFunction[A, Unit]): Unit = SeqOps.foreachPartial(self, pf)
 
     /**
      * Chooses last element in seq when key collision occurs
      */
+    @deprecated("Use com.twitter.conversions.SeqOps#groupBySingleValue instead", "2020-11-16")
     def groupBySingleValue[B](keys: A => B): Map[B, A] = {
       createMap(keys, identity)
     }
 
-    def findItemAfter(itemToFind: A): Option[A] = {
-      @tailrec
-      def recurse(itemToFind: A, seq: Seq[A]): Option[A] = seq match {
-        case Seq(x, xs @ _*) if x == itemToFind => xs.headOption
-        case Seq(x, xs @ _*) => recurse(itemToFind, xs)
-        case Seq() => None
-      }
-      recurse(itemToFind, self)
-    }
+    @deprecated("Use com.twitter.conversions.SeqOps#findItemAfter instead", "2020-11-16")
+    def findItemAfter(itemToFind: A): Option[A] = SeqOps.findItemAfter(self, itemToFind)
   }
 }