Nullness: add annotation for java.lang

src/java.base/share/classes/java/io/ObjectInputStream.java

@@ -479,7 +479,7 @@ protected ObjectInputStream() throws IOException, SecurityException {
      *          stream instead of objects.
      * @throws  IOException Any of the usual Input/Output related exceptions.
      */
-    public final @Nullable Object readObject()
+    public final Object readObject()
         throws IOException, ClassNotFoundException {
         return readObject(Object.class);
     }

src/java.base/share/classes/java/lang/AbstractStringBuilder.java

@@ -612,7 +612,7 @@ public AbstractStringBuilder append(@Nullable StringBuffer sb) {
     /**
      * @since 1.8
      */
-    AbstractStringBuilder append(AbstractStringBuilder asb) {
+    AbstractStringBuilder append(@Nullable AbstractStringBuilder asb) {
         if (asb == null) {
             return appendNull();
         }
@@ -1676,6 +1676,7 @@ void getBytes(byte[] dst, int dstBegin, byte coder) {
     }
 
     /* for readObject() */
+    @SuppressWarnings("nullness:assignment.type.incompatible") // This like a false positive to me
     void initBytes(char[] value, int off, int len) {
         if (String.COMPACT_STRINGS) {
             this.value = StringUTF16.compress(value, off, len);

src/java.base/share/classes/java/lang/ApplicationShutdownHooks.java

@@ -25,6 +25,7 @@
 package java.lang;
 
 import org.checkerframework.checker.interning.qual.UsesObjectEquals;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 import java.util.*;
@@ -40,7 +41,7 @@
 @AnnotatedFor({"interning"})
 @UsesObjectEquals class ApplicationShutdownHooks {
     /* The set of registered hooks */
-    private static IdentityHashMap<Thread, Thread> hooks;
+    private static @Nullable IdentityHashMap<Thread, Thread> hooks;
     static {
         try {
             Shutdown.add(1 /* shutdown hook invocation order */,
@@ -95,6 +96,7 @@ static synchronized boolean remove(Thread hook) {
      * to run in. Hooks are run concurrently and this method waits for
      * them to finish.
      */
+    @SuppressWarnings("nullness:dereference.of.nullable") // AOSEN: hooks is null only if illegal state exception is thrown
     static void runHooks() {
         Collection<Thread> threads;
         synchronized(ApplicationShutdownHooks.class) {

src/java.base/share/classes/java/lang/Boolean.java

@@ -313,7 +313,7 @@ public boolean equals(@Nullable Object obj) {
     @Pure
     @StaticallyExecutable
     @EnsuresNonNullIf(expression="#1", result=true)
-    public static boolean getBoolean(@Nullable String name) {
+    public static boolean getBoolean(String name) {
         boolean result = false;
         try {
             result = parseBoolean(System.getProperty(name));

src/java.base/share/classes/java/lang/Character.java

@@ -3813,7 +3813,7 @@ private UnicodeBlock(String idName, String... aliases) {
             0x100000, // 100000..10FFFF; Supplementary Private Use Area-B
         };
 
-        private static final UnicodeBlock[] blocks = {
+        private static final @Nullable UnicodeBlock[] blocks = {
             BASIC_LATIN,
             LATIN_1_SUPPLEMENT,
             LATIN_EXTENDED_A,
@@ -11474,7 +11474,7 @@ static int toUpperCaseEx(int codePoint) {
      */
     @SideEffectFree
     @StaticallyExecutable
-    static char[] toUpperCaseCharArray(int codePoint) {
+    static char @Nullable [] toUpperCaseCharArray(int codePoint) {
         // As of Unicode 6.0, 1:M uppercasings only happen in the BMP.
         assert isBmpCodePoint(codePoint);
         return CharacterData.of(codePoint).toUpperCaseCharArray(codePoint);
@@ -11542,7 +11542,7 @@ public static char reverseBytes(char ch) {
      */
     @Pure
     @StaticallyExecutable
-    public static String getName(int codePoint) {
+    public static @Nullable String getName(int codePoint) {
         if (!isValidCodePoint(codePoint)) {
             throw new IllegalArgumentException(
                 String.format("Not a valid Unicode code point: 0x%X", codePoint));

src/java.base/share/classes/java/lang/CharacterData.java

@@ -26,6 +26,7 @@
 package java.lang;
 
 import org.checkerframework.checker.interning.qual.UsesObjectEquals;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -55,7 +56,7 @@ int toUpperCaseEx(int ch) {
         return toUpperCase(ch);
     }
 
-    char[] toUpperCaseCharArray(int ch) {
+    char @Nullable [] toUpperCaseCharArray(int ch) {
         return null;
     }
 

src/java.base/share/classes/java/lang/CharacterName.java

@@ -26,6 +26,7 @@
 package java.lang;
 
 import org.checkerframework.checker.interning.qual.UsesObjectEquals;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 import java.io.DataInputStream;
@@ -54,6 +55,7 @@
     private CharacterName()  {
         try (@SuppressWarnings("removal") DataInputStream dis = new DataInputStream(new InflaterInputStream(
             AccessController.doPrivileged(new PrivilegedAction<>() {
+                @SuppressWarnings("nullness:return.type.incompatible")
                 public InputStream run() {
                     return getClass().getResourceAsStream("uniName.dat");
                 }
@@ -144,7 +146,7 @@ public static CharacterName getInstance() {
         return cname;
     }
 
-    public String getName(int cp) {
+    public @Nullable String getName(int cp) {
         int off = 0;
         int bk = bkIndices[cp >> 8];
         if (bk == -1 || (off = lookup[(bk << 8) + (cp & 0xff)]) == 0)