new inference: choose most specifics between 2 varargs methods

(cherry picked from commit 9f754331ad04e4be639d94da7a659927f8384294)

java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/InferenceSession.java

@@ -928,7 +928,7 @@ public class InferenceSession {
     }
 
     if (varargs) {
-      PsiType sType = siteSubstitutor2.substitute(parameters1[paramsLength].getType());
+      PsiType sType = siteSubstitutor2.substitute(getVarargParameterType(true, paramsLength, parameters1));
       PsiType tType = siteSubstitutor2.substitute(getVarargParameterType(true, paramsLength, parameters2));
       session.addConstraint(new StrictSubtypingConstraint(tType, sType));
     }
@@ -939,8 +939,9 @@ public class InferenceSession {
   public static PsiType getVarargParameterType(boolean varargs, int i, PsiParameter[] parameters2) {
     if (varargs && i >= parameters2.length - 1) {
       final PsiType lastParamType = parameters2[parameters2.length - 1].getType();
-      LOG.assertTrue(lastParamType instanceof PsiEllipsisType);
-      return ((PsiEllipsisType)lastParamType).getComponentType();
+      if (lastParamType instanceof PsiEllipsisType) {
+        return ((PsiEllipsisType)lastParamType).getComponentType();
+      }
     }
     return parameters2[i].getType();
   }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/mostSpecific/BothVarargs.java

@@ -0,0 +1,14 @@
+import java.util.List;
+
+abstract class StreamMain {
+  public abstract  <T> Iterable<T> concat(final Iterable<? extends T>... iterables);
+  public abstract  <T> Iterable<T> concat(final List<? extends T>... iterables);
+
+
+  public final List<String> errorFixesToShow = null;
+  public final List<String> inspectionFixesToShow = null;
+
+  {
+    concat(errorFixesToShow,   inspectionFixesToShow);
+  }
+}

java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/MostSpecificResolutionTest.java

@@ -43,6 +43,10 @@ public class MostSpecificResolutionTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testBothVarargs() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(true);
   }