Fix a bunch of compiler warnings by adding @SuppressWarnings("unchecked") to code generated by @AutoCodec.

PiperOrigin-RevId: 257294445
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec/AutoCodecUtil.java b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec/AutoCodecUtil.java
index ce2a3f4..740ff8c 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec/AutoCodecUtil.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/serialization/autocodec/AutoCodecUtil.java
@@ -21,6 +21,7 @@
 import com.google.devtools.build.lib.skyframe.serialization.SerializationException;
 import com.google.protobuf.CodedInputStream;
 import com.google.protobuf.CodedOutputStream;
+import com.squareup.javapoet.AnnotationSpec;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.MethodSpec;
 import com.squareup.javapoet.ParameterizedTypeName;
@@ -80,6 +81,10 @@
             .addModifiers(Modifier.PUBLIC)
             .returns(void.class)
             .addAnnotation(Override.class)
+            .addAnnotation(
+                AnnotationSpec.builder(ClassName.get(SuppressWarnings.class))
+                    .addMember("value", "$S", "unchecked")
+                    .build())
             .addException(SerializationException.class)
             .addException(IOException.class)
             .addParameter(SerializationContext.class, "context")