Add Expression.asBoolean()

Author: wu-hui

firebase-firestore/src/main/java/com/google/firebase/firestore/RealtimePipeline.kt

@@ -24,13 +24,13 @@ import com.google.firebase.firestore.model.Document
 import com.google.firebase.firestore.model.MutableDocument
 import com.google.firebase.firestore.model.ResourcePath
 import com.google.firebase.firestore.pipeline.BooleanExpression
+import com.google.firebase.firestore.pipeline.BooleanFunctionExpression
 import com.google.firebase.firestore.pipeline.CollectionGroupOptions
 import com.google.firebase.firestore.pipeline.CollectionGroupSource
 import com.google.firebase.firestore.pipeline.CollectionSource
 import com.google.firebase.firestore.pipeline.CollectionSourceOptions
 import com.google.firebase.firestore.pipeline.EvaluationContext
 import com.google.firebase.firestore.pipeline.Field
-import com.google.firebase.firestore.pipeline.FunctionExpression
 import com.google.firebase.firestore.pipeline.InternalOptions
 import com.google.firebase.firestore.pipeline.LimitStage
 import com.google.firebase.firestore.pipeline.OffsetStage
@@ -384,9 +384,9 @@ internal constructor(
       // Check for Where stage
       if (stage is WhereStage) {
         // Check if it's the special 'exists(__name__)' case
-        val funcExpr = stage.condition as? FunctionExpression
-        if (funcExpr?.name == "exists" && funcExpr.params.size == 1) {
-          val fieldExpr = funcExpr.params[0] as? Field
+        val funcExpr = stage.condition as? BooleanFunctionExpression
+        if (funcExpr?.expr?.name == "exists" && funcExpr.expr.params.size == 1) {
+          val fieldExpr = funcExpr?.expr?.params[0] as? Field
           if (fieldExpr?.fieldPath?.isKeyField == true) {
             continue // This specific 'exists(__name__)' filter doesn't count
           }