Add Nonnull to String.valueOf
Otherwise JsCompiler thinks that String.valueOf(a) + 1 might
result in number.
Change-Id: I2954d21c279a430b60ab2aebfdf6586180223dd2
diff --git a/user/super/com/google/gwt/emul/java/lang/String.java b/user/super/com/google/gwt/emul/java/lang/String.java
index 0fe193a..bb23493 100644
--- a/user/super/com/google/gwt/emul/java/lang/String.java
+++ b/user/super/com/google/gwt/emul/java/lang/String.java
@@ -27,12 +27,15 @@
import java.util.Locale;
import java.util.StringJoiner;
+import javax.annotation.Nonnull;
+
import javaemul.internal.ArrayHelper;
import javaemul.internal.EmulatedCharset;
import javaemul.internal.HashCodes;
import javaemul.internal.JsUtils;
import javaemul.internal.NativeRegExp;
import javaemul.internal.annotations.DoNotInline;
+
import jsinterop.annotations.JsMethod;
import jsinterop.annotations.JsPackage;
import jsinterop.annotations.JsProperty;
@@ -186,6 +189,7 @@
// valueOf needs to be treated special:
// J2cl uses it for String concat and thus it can not use string concatenation itself.
+ @Nonnull
public static String valueOf(Object x) {
return x == null ? "null" : x.toString();
}