revert some change

packages/@aws-cdk/core/lib/cfn-element.ts

@@ -1,5 +1,5 @@
 import * as cxapi from '@aws-cdk/cx-api';
-import { Construct, IConstruct } from "./construct-compat";
+import { Construct } from "./construct-compat";
 import { Lazy } from "./lazy";
 import { Token } from './token';
 
@@ -22,30 +22,6 @@ export abstract class CfnElement extends Construct {
     return CFN_ELEMENT_SYMBOL in x;
   }
 
-  /**
-   * Finds all CfnElements in a scope (does not recurse into sub-stacks).
-   *
-   * @param node Root node to collect all CfnElements from
-   * @param into Array to append CfnElements to
-   * @returns The same array as is being collected into
-   *
-   * @internal
-   */
-  public static _findAll(node: IConstruct, into: CfnElement[] = []): CfnElement[] {
-    if (CfnElement.isCfnElement(node)) {
-      into.push(node);
-    }
-
-    for (const child of node.node.children) {
-      // Don't recurse into a substack
-      if (Stack.isStack(child)) { continue; }
-
-      this._findAll(child, into);
-    }
-
-    return into;
-  }
-
   /**
    * The logical ID for this CloudFormation stack element. The logical ID of the element
    * is calculated from the path of the resource node in the construct tree.

packages/@aws-cdk/core/lib/stack.ts

@@ -856,7 +856,7 @@ export class Stack extends Construct implements ITaggable {
       Metadata: this.templateOptions.metadata
     };
 
-    const elements = CfnElement._findAll(this);
+    const elements = cfnElements(this);
     const fragments = elements.map(e => this.resolve(e._toCloudFormation()));
 
     // merge in all CloudFormation fragments collected from the tree
@@ -1001,6 +1001,28 @@ function merge(template: any, part: any) {
   }
 }
 
+/**
+ * Collect all CfnElements from a Stack.
+ *
+ * @param node Root node to collect all CfnElements from
+ * @param into Array to append CfnElements to
+ * @returns The same array as is being collected into
+ */
+function cfnElements(node: IConstruct, into: CfnElement[] = []): CfnElement[] {
+  if (CfnElement.isCfnElement(node)) {
+    into.push(node);
+  }
+
+  for (const child of node.node.children) {
+    // Don't recurse into a substack
+    if (Stack.isStack(child)) { continue; }
+
+    cfnElements(child, into);
+  }
+
+  return into;
+}
+
 /**
  * CloudFormation template options for a stack.
  */