Try to retrieve schema from all schemas cache if not found in individual cache (#2912)

* Try to get schema from main schema if not found in single schema

* Add newline

* Add missing return

* Add missing done to tests

src/Controllers/SchemaCache.js

@@ -50,7 +50,21 @@ export default class SchemaCache {
     if (!this.ttl) {
       return Promise.resolve(null);
     }
-    return this.cache.get(this.prefix+className);
+    return this.cache.get(this.prefix+className).then((schema) => {
+      if (schema) {
+        return Promise.resolve(schema);
+      }
+      return this.cache.get(this.prefix+MAIN_SCHEMA).then((cachedSchemas) => {
+        cachedSchemas = cachedSchemas || [];
+        schema = cachedSchemas.find((cachedSchema) => {
+          return cachedSchema.className === className;
+        });
+        if (schema) {
+          return Promise.resolve(schema);
+        }
+        return Promise.resolve(null);
+      });
+    });
   }
 
   clear() {