Minor fixes in CFG Stream inlining

1. Initial stream element nullability is derived from type
2. reportNullableArgumentsPassedToNonAnnotated fixed for method references

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DataFlowInspectionBase.java

@@ -551,6 +551,11 @@ public class DataFlowInspectionBase extends BaseJavaBatchLocalInspectionTool {
     for (PsiElement expr : visitor.getProblems(NullabilityProblem.passingNullableArgumentToNonAnnotatedParameter)) {
       if (reportedAnchors.contains(expr)) continue;
 
+      if (expr.getParent() instanceof PsiMethodReferenceExpression) {
+        holder.registerProblem(expr.getParent(), "Method reference argument might be null but passed to non annotated parameter");
+        continue;
+      }
+
       final String text = isNullLiteralExpression(expr)
                           ? "Passing <code>null</code> argument to non annotated parameter"
                           : "Argument <code>#ref</code> #loc might be null but passed to non annotated parameter";

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/inliner/StreamChainInliner.java

@@ -317,7 +317,7 @@ public class StreamChainInliner implements CallInliner {
       .chain(firstStep::before)
       .doWhile()
       .pushVariable(builder.createTempVariable(inType))
-      .push(builder.getFactory().createTypeValue(inType, Nullness.UNKNOWN))
+      .push(builder.getFactory().createTypeValue(inType, DfaPsiUtil.getTypeNullability(inType)))
       .assign()
       .chain(firstStep::iteration)
       .endWhileUnknown();