fix: new IAM Condition type is unusable in Java (aws#7270)

The changing of the type of `Condition` from `any` to `Record<string,
any>` broke common code in Java.

Many users would be passing a `Map<String, String>` in that location,
which WOULD be assignable to the old type `Object`, but not to the
new type `Map<String, Object>`.

Revert for now and turn this into a feature request to jsii team.

allowed-breaking-changes.txt

@@ -46,3 +46,6 @@ incompatible-argument:@aws-cdk/aws-iam.PolicyStatement.addCondition
 incompatible-argument:@aws-cdk/aws-iam.PolicyStatement.addConditions
 incompatible-argument:@aws-cdk/aws-iam.PolicyStatement.addFederatedPrincipal
 incompatible-argument:@aws-cdk/aws-iam.PrincipalPolicyFragment.<initializer>
+changed-type:@aws-cdk/aws-iam.FederatedPrincipal.conditions
+changed-type:@aws-cdk/aws-iam.PrincipalPolicyFragment.conditions
+changed-type:@aws-cdk/aws-iam.PrincipalWithConditions.conditions

packages/@aws-cdk/aws-iam/lib/policy-statement.ts

@@ -307,7 +307,19 @@ export enum Effect {
  * Condition for when an IAM policy is in effect. Maps from the keys in a request's context to
  * a string value or array of string values. See the Conditions interface for more details.
  */
-export type Condition = Record<string, any>;
+export type Condition = any;
+
+// NOTE! We'd ideally like to type this as `Record<string, any>`, because the
+// API expects a map which can take either strings or lists of strings.
+//
+// However, if we were to change this right now, the Java bindings for CDK would
+// emit a type of `Map<String, Object>`, but the most common types people would
+// instantiate would be an `ImmutableMap<String, String>` which would not be
+// assignable to `Map<String, Object>`. The types don't have a built-in notion
+// of co-contravariance, you have to indicate that on the type. So jsii would first
+// need to emit the type as `Map<String, ? extends Object>`.
+//
+// Feature request in https://github.com/aws/jsii/issues/1517
 
 /**
  * Conditions for when an IAM Policy is in effect, specified in the following structure: