[Tiered Caching] Add a memory-efficient key lookup store for use in tiered cache

plugins/cache-ehcache/build.gradle

@@ -23,7 +23,12 @@ versions << [
 ]
 
 dependencies {
+  // For ehcache
   api "org.ehcache:ehcache:${versions.ehcache}"
+
+  // For roaring bitmaps
+  api 'org.roaringbitmap:RoaringBitmap:0.9.49'
+  runtimeOnly 'org.roaringbitmap:shims:0.9.49'
 }
 
 thirdPartyAudit {

plugins/cache-ehcache/licenses/RoaringBitmap-0.9.49.jar.sha1

@@ -0,0 +1 @@
+b45b49c1ec5c5fc48580412d0ca635e1833110ea

plugins/cache-ehcache/licenses/RoaringBitmap-LICENSE.txt

@@ -0,0 +1,191 @@
+Apache License
+Version 2.0, January 2004
+http://www.apache.org/licenses/
+
+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+1. Definitions.
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plugins/cache-ehcache/licenses/shims-0.9.49.jar.sha1

@@ -0,0 +1 @@
+8bd7794fbdaa9536354dd2d8d961d9503beb9460