Switch to JSpecify annotations

Now, hear me out, what if instead of having three @Nullable annotations,
we had *four*?

I've been wanting to switch away from javax.annoations for a while. The
library has been deprecated for ever and, unlike other @Nullable
annotations, the annotation is attached to the parameter/function
itself, rather than the type.

We use JSpecify rather than one of the alternatives (JetBrains,
CheckerFramework) mostly because it's what NullAway recommends. We keep
CheckerFramework around for @DefaultQualifier, and JB's for @Contract.

There are some ugly changes here — for instance, `@Nullable byte[]` is
replace by `byte @Nullable`, and `@Nullable ILuaMachine.Factory` is
`ILuaMachine.@Nullable Factory`. Ughr, I understand why, but it does not
spark joy :).

projects/web/src/builder/java/cc/tweaked/web/builder/PatchCobalt.java

@@ -4,13 +4,12 @@
 
 package cc.tweaked.web.builder;
 
+import org.jspecify.annotations.Nullable;
 import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.Label;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;
 
-import javax.annotation.Nullable;
-
 import static org.objectweb.asm.Opcodes.*;
 
 /**

projects/web/src/builder/java/cc/tweaked/web/builder/TransformingClassLoader.java

@@ -4,13 +4,13 @@
 
 package cc.tweaked.web.builder;
 
+import org.jspecify.annotations.Nullable;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassVisitor;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.commons.ClassRemapper;
 import org.objectweb.asm.commons.Remapper;
 
-import javax.annotation.Nullable;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;

projects/web/src/main/java/cc/tweaked/web/EmulatedComputer.java

@@ -21,13 +21,13 @@ import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.filesystem.MemoryMount;
 import dan200.computercraft.core.metrics.MetricsObserver;
 import dan200.computercraft.core.terminal.Terminal;
+import org.jspecify.annotations.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.teavm.jso.JSObject;
 import org.teavm.jso.core.JSString;
 import org.teavm.jso.typedarrays.ArrayBuffer;
 
-import javax.annotation.Nullable;
 import java.nio.charset.StandardCharsets;
 import java.util.Arrays;
 import java.util.Objects;

projects/web/src/main/java/cc/tweaked/web/EmulatorEnvironment.java

@@ -7,8 +7,8 @@ package cc.tweaked.web;
 import cc.tweaked.web.js.Callbacks;
 import dan200.computercraft.api.filesystem.Mount;
 import dan200.computercraft.core.computer.GlobalEnvironment;
+import org.jspecify.annotations.Nullable;
 
-import javax.annotation.Nullable;
 import java.io.ByteArrayInputStream;
 import java.io.InputStream;
 
@@ -21,7 +21,7 @@ final class EmulatorEnvironment implements GlobalEnvironment {
 
     private final String version = Callbacks.getModVersion();
     private @Nullable ResourceMount romMount;
-    private @Nullable byte[] bios;
+    private byte @Nullable [] bios;
 
     private EmulatorEnvironment() {
     }

projects/web/src/main/java/cc/tweaked/web/ResourceMount.java

@@ -7,8 +7,8 @@ package cc.tweaked.web;
 import cc.tweaked.web.js.Callbacks;
 import dan200.computercraft.core.apis.handles.ArrayByteChannel;
 import dan200.computercraft.core.filesystem.AbstractInMemoryMount;
+import org.jspecify.annotations.Nullable;
 
-import javax.annotation.Nullable;
 import java.nio.channels.SeekableByteChannel;
 
 /**
@@ -43,7 +43,7 @@ final class ResourceMount extends AbstractInMemoryMount<ResourceMount.FileEntry>
 
     protected static final class FileEntry extends AbstractInMemoryMount.FileEntry<FileEntry> {
         private final String path;
-        private @Nullable byte[] contents;
+        private byte @Nullable [] contents;
 
         FileEntry(String path) {
             this.path = path;

projects/web/src/main/java/cc/tweaked/web/js/ComputerDisplay.java

@@ -4,10 +4,9 @@
 
 package cc.tweaked.web.js;
 
+import org.jspecify.annotations.Nullable;
 import org.teavm.jso.JSObject;
 
-import javax.annotation.Nullable;
-
 /**
  * The Javascript-side terminal which displays this computer.
  *

projects/web/src/main/java/cc/tweaked/web/js/ComputerHandle.java

@@ -4,13 +4,12 @@
 
 package cc.tweaked.web.js;
 
+import org.jspecify.annotations.Nullable;
 import org.teavm.jso.JSObject;
 import org.teavm.jso.JSProperty;
 import org.teavm.jso.core.JSString;
 import org.teavm.jso.typedarrays.ArrayBuffer;
 
-import javax.annotation.Nullable;
-
 /**
  * A Javascript-facing interface for controlling computers.
  */

projects/web/src/main/java/cc/tweaked/web/js/JavascriptConv.java

@@ -5,6 +5,7 @@
 package cc.tweaked.web.js;
 
 import org.jetbrains.annotations.Contract;
+import org.jspecify.annotations.Nullable;
 import org.teavm.jso.JSBody;
 import org.teavm.jso.JSByRef;
 import org.teavm.jso.JSObject;
@@ -15,7 +16,6 @@ import org.teavm.jso.core.JSString;
 import org.teavm.jso.typedarrays.ArrayBuffer;
 import org.teavm.jso.typedarrays.Int8Array;
 
-import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 
 /**
@@ -29,7 +29,7 @@ public class JavascriptConv {
      * @return The converted value.
      */
     @Contract("null -> null; !null -> !null")
-    public static @Nullable Object[] toJava(@Nullable JSObject[] value) {
+    public static @Nullable Object @Nullable [] toJava(@Nullable JSObject @Nullable [] value) {
         if (value == null) return null;
         var out = new Object[value.length];
         for (var i = 0; i < value.length; i++) out[i] = toJava(value[i]);

projects/web/src/main/java/cc/tweaked/web/peripheral/AudioState.java

@@ -6,10 +6,10 @@ package cc.tweaked.web.peripheral;
 
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.LuaTable;
+import org.jspecify.annotations.Nullable;
 import org.teavm.jso.webaudio.AudioBuffer;
 import org.teavm.jso.webaudio.AudioContext;
 
-import javax.annotation.Nullable;
 import java.util.Optional;
 
 import static cc.tweaked.web.peripheral.SpeakerPeripheral.SAMPLE_RATE;

projects/web/src/main/java/cc/tweaked/web/peripheral/SpeakerPeripheral.java

@@ -10,9 +10,9 @@ import dan200.computercraft.api.lua.LuaTable;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.jspecify.annotations.Nullable;
 import org.teavm.jso.webaudio.AudioContext;
 
-import javax.annotation.Nullable;
 import java.util.Optional;
 
 import static dan200.computercraft.api.lua.LuaValues.checkFinite;

projects/web/src/main/java/dan200/computercraft/core/apis/http/request/THttpRequest.java

@@ -16,12 +16,12 @@ import dan200.computercraft.core.apis.http.ResourceGroup;
 import io.netty.handler.codec.http.HttpHeaderNames;
 import io.netty.handler.codec.http.HttpHeaders;
 import io.netty.handler.codec.http.HttpMethod;
+import org.jspecify.annotations.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.teavm.jso.ajax.XMLHttpRequest;
 import org.teavm.jso.typedarrays.ArrayBuffer;
 
-import javax.annotation.Nullable;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.nio.ByteBuffer;

projects/web/src/main/java/dan200/computercraft/core/apis/http/websocket/TWebsocket.java

@@ -13,10 +13,10 @@ import dan200.computercraft.core.apis.http.ResourceGroup;
 import dan200.computercraft.core.apis.http.options.Action;
 import dan200.computercraft.core.apis.http.options.Options;
 import io.netty.handler.codec.http.HttpHeaders;
+import org.jspecify.annotations.Nullable;
 import org.teavm.jso.typedarrays.Int8Array;
 import org.teavm.jso.websocket.WebSocket;
 
-import javax.annotation.Nullable;
 import java.net.URI;
 import java.nio.ByteBuffer;
 

projects/web/src/main/java/dan200/computercraft/core/asm/MethodReflection.java

@@ -13,9 +13,9 @@ import dan200.computercraft.api.lua.MethodResult;
 import dan200.computercraft.api.peripheral.PeripheralType;
 import dan200.computercraft.core.methods.LuaMethod;
 import dan200.computercraft.core.methods.NamedMethod;
+import org.jspecify.annotations.Nullable;
 import org.teavm.metaprogramming.*;
 
-import javax.annotation.Nullable;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.util.ArrayList;

projects/web/src/main/java/dan200/computercraft/core/asm/StaticGenerator.java

@@ -11,12 +11,12 @@ import com.google.common.primitives.Primitives;
 import com.google.common.reflect.TypeToken;
 import dan200.computercraft.api.lua.*;
 import dan200.computercraft.core.methods.LuaMethod;
+import org.jspecify.annotations.Nullable;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Type;
 import org.teavm.metaprogramming.ReflectClass;
 
-import javax.annotation.Nullable;
 import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.nio.ByteBuffer;
@@ -124,8 +124,7 @@ public final class StaticGenerator<T> {
         }
     }
 
-    @Nullable
-    private byte[] generate(String className, Class<?> target, Method targetMethod, boolean unsafe) {
+    private byte @Nullable [] generate(String className, Class<?> target, Method targetMethod, boolean unsafe) {
         var internalName = className.replace(".", "/");
 
         // Construct a public final class which extends Object and implements MethodInstance.Delegate
@@ -207,8 +206,7 @@ public final class StaticGenerator<T> {
         return cw.toByteArray();
     }
 
-    @Nullable
-    private Boolean loadArg(MethodVisitor mw, Class<?> target, Method method, boolean unsafe, java.lang.reflect.Type genericArg, int argIndex) {
+    private @Nullable Boolean loadArg(MethodVisitor mw, Class<?> target, Method method, boolean unsafe, java.lang.reflect.Type genericArg, int argIndex) {
         if (genericArg == target) {
             mw.visitVarInsn(ALOAD, 1);
             mw.visitTypeInsn(CHECKCAST, Type.getInternalName(target));