Make default value for -Xjsr305 flag to be WARN

compiler/testData/cli/jvm/jsr305/A.java

@@ -0,0 +1,4 @@
+@javax.annotation.ParametersAreNonnullByDefault
+public class A {
+    public void foo(String x) {}
+}

compiler/testData/cli/jvm/jsr305/javax/annotation/ParametersAreNonnullByDefault.java

@@ -0,0 +1,28 @@
+package javax.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * This annotation can be applied to a package, class or method to indicate that
+ * the method parameters in that element are nonnull by default unless there is:
+ * <ul>
+ * <li>An explicit nullness annotation
+ * <li>The method overrides a method in a superclass (in which case the
+ * annotation of the corresponding parameter in the superclass applies)
+ * <li>There is a default parameter annotation (like {@link ParametersAreNullableByDefault})
+ * applied to a more tightly nested element.
+ * </ul>
+ *
+ * @see Nonnull
+ */
+@Documented
+@Nonnull
+@TypeQualifierDefault(ElementType.PARAMETER)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface ParametersAreNonnullByDefault {
+}

compiler/testData/cli/jvm/jsr305NoFlag.args

@@ -0,0 +1,4 @@
+$TESTDATA_DIR$/jsr305Usage.kt
+$TESTDATA_DIR$/jsr305
+-d
+$TEMP_DIR$

compiler/testData/cli/jvm/jsr305NoFlag.out

@@ -0,0 +1,4 @@
+compiler/testData/cli/jvm/jsr305Usage.kt:2:11: warning: expected type does not accept nulls in Java, but the value may be null in Kotlin
+    a.foo(null)
+          ^
+OK