lambda: skip conditional condition during inference from return value

java/java-psi-api/src/com/intellij/psi/LambdaUtil.java

@@ -311,6 +311,18 @@ public class LambdaUtil {
     if (lambdaParams.length != methodParameters.length) return false;
     final boolean [] independent = new boolean[]{true};
     expression.accept(new JavaRecursiveElementWalkingVisitor() {
+      @Override
+      public void visitConditionalExpression(PsiConditionalExpression expression) {
+        final PsiExpression thenExpression = expression.getThenExpression();
+        if (thenExpression != null) {
+          thenExpression.accept(this);
+        }
+        final PsiExpression elseExpression = expression.getElseExpression();
+        if (elseExpression != null) {
+          elseExpression.accept(this);
+        }
+      }
+
       @Override
       public void visitReferenceExpression(PsiReferenceExpression expression) {
         super.visitReferenceExpression(expression);

java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/PsiResolveHelperImpl.java

@@ -605,7 +605,12 @@ public class PsiResolveHelperImpl implements PsiResolveHelper {
         final List<PsiExpression> expressions = lambdaExpression.getReturnExpressions();
         for (final PsiExpression expression : expressions) {
           final boolean independent = LambdaUtil.isFreeFromTypeInferenceArgs(methodParameters, lambdaExpression, expression);
-          if (independent && methodParamsDependOnTypeParams) return FAILED_INFERENCE;
+          if (independent && methodParamsDependOnTypeParams ) {
+            if (lowerBound != PsiType.NULL) {
+              return null;
+            }
+            return FAILED_INFERENCE;
+          }
           if (!independent) {
             if (lowerBound != PsiType.NULL) {
               return null;

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/highlighting/ConditionalExpr.java

@@ -37,3 +37,15 @@ class Test {
   }
 }
 
+class Test1 {
+  interface I<T, V> {
+    V _(T t);
+  }
+
+  static <V> void bar(I<String, V> ii, I<V, String> ik){}
+
+  {
+    bar(s -> s.equals("") ? 0 : 1, i -> "");
+  }
+}
+