fix some warnings

Author: laurit

conventions/src/main/kotlin/otel.errorprone-conventions.gradle.kts

@@ -140,6 +140,7 @@ tasks {
           // This check causes too many failures, ignore the ones in tests
           disable("OtelCanIgnoreReturnValueSuggester")
           disable("OtelInternalJavadoc")
+          disable("SuppressWarningsWithoutExplanation")
         }
       }
     }

declarative-config-bridge/src/main/java/io/opentelemetry/instrumentation/config/bridge/DeclarativeConfigPropertiesBridge.java

@@ -16,6 +16,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.BiFunction;
+import java.util.function.Function;
 import javax.annotation.Nullable;
 
 /**
@@ -106,18 +107,17 @@ public Duration getDuration(String propertyName) {
     return Duration.ofMillis(millis);
   }
 
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings("unchecked") // we expect to have only lists of strings in override values
   @Override
   public List<String> getList(String propertyName) {
     List<String> propertyValue =
         getPropertyValue(
             propertyName,
-            List.class,
+            o -> (List<String>) o,
             (properties, lastPart) -> properties.getScalarList(lastPart, String.class));
     return propertyValue == null ? Collections.emptyList() : propertyValue;
   }
 
-  @SuppressWarnings("unchecked")
   @Override
   public Map<String, String> getMap(String propertyName) {
     DeclarativeConfigProperties propertyValue =
@@ -147,7 +147,15 @@ private <T> T getPropertyValue(
       String property,
       Class<T> clazz,
       BiFunction<DeclarativeConfigProperties, String, T> extractor) {
-    T override = clazz.cast(overrideValues.get(property));
+    return getPropertyValue(property, clazz::cast, extractor);
+  }
+
+  @Nullable
+  private <T> T getPropertyValue(
+      String property,
+      Function<Object, T> converter,
+      BiFunction<DeclarativeConfigProperties, String, T> extractor) {
+    T override = converter.apply(overrideValues.get(property));
     if (override != null) {
       return override;
     }

instrumentation-annotations-support/src/main/java/io/opentelemetry/instrumentation/api/annotation/support/AnnotationReflectionHelper.java

@@ -6,8 +6,6 @@
 package io.opentelemetry.instrumentation.api.annotation.support;
 
 import java.lang.annotation.Annotation;
-import java.lang.invoke.CallSite;
-import java.lang.invoke.LambdaMetafactory;
 import java.lang.invoke.MethodHandle;
 import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodType;
@@ -65,6 +63,7 @@ public static Class<? extends Annotation> forNameOrNull(
    * @throws NoSuchMethodException the annotation element method was not found
    * @throws Throwable on failing to bind to the
    */
+  @SuppressWarnings("unchecked") // need to cast the return value for MethodHandle.invoke
   public static <A extends Annotation, T> Function<A, T> bindAnnotationElementMethod(
       MethodHandles.Lookup lookup,
       Class<? extends Annotation> annotationClass,
@@ -75,19 +74,12 @@ public static <A extends Annotation, T> Function<A, T> bindAnnotationElementMeth
     MethodHandle valueHandle =
         lookup.findVirtual(annotationClass, methodName, MethodType.methodType(returnClass));
 
-    CallSite callSite =
-        LambdaMetafactory.metafactory(
-            lookup,
-            "apply",
-            MethodType.methodType(Function.class),
-            MethodType.methodType(Object.class, Object.class),
-            valueHandle,
-            MethodType.methodType(returnClass, annotationClass));
-
-    MethodHandle factory = callSite.getTarget();
-
-    @SuppressWarnings("unchecked")
-    Function<A, T> function = (Function<A, T>) factory.invoke();
-    return function;
+    return a -> {
+      try {
+        return (T) valueHandle.invoke(a);
+      } catch (Throwable e) {
+        throw new IllegalStateException(e);
+      }
+    };
   }
 }

instrumentation-annotations-support/src/main/java/io/opentelemetry/instrumentation/api/annotation/support/AttributeBindingFactory.java

@@ -114,7 +114,7 @@ private static AttributeBinding arrayBinding(String name, Type type) {
     return defaultArrayBinding(name);
   }
 
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings("unchecked") // safe because type is checked before casting
   private static AttributeBinding listBinding(String name, Type componentType) {
     if (componentType == String.class) {
       AttributeKey<List<String>> key = AttributeKey.stringArrayKey(name);
@@ -310,7 +310,7 @@ public int size() {
   private static <T, U> AttributeBinding mappedListBinding(
       AttributeKey<List<U>> key, Function<T, U> mapping) {
     return (setter, arg) -> {
-      @SuppressWarnings("unchecked")
+      @SuppressWarnings("unchecked") // safe because we only call this method for lists
       List<T> list = (List<T>) arg;
       List<U> wrapper =
           new AbstractList<U>() {

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/Instrumenter.java

@@ -85,6 +85,7 @@ public static <REQUEST, RESPONSE> InstrumenterBuilder<REQUEST, RESPONSE> builder
   private final boolean enabled;
   private final SpanSuppressor spanSuppressor;
 
+  // to allow converting generic lists to arrays with toArray
   @SuppressWarnings({"rawtypes", "unchecked"})
   Instrumenter(InstrumenterBuilder<REQUEST, RESPONSE> builder) {
     this.instrumentationName = builder.instrumentationName;

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/instrumenter/UnsafeAttributes.java

@@ -28,7 +28,7 @@ final class UnsafeAttributes extends HashMap<AttributeKey<?>, Object>
 
   // Attributes
 
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings("unchecked") // safe because of the AttributeKey<T> typing
   @Override
   @Nullable
   public <T> T get(AttributeKey<T> key) {

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/Experimental.java

@@ -55,7 +55,7 @@ public static <REQUEST> void setUrlTemplateExtractor(
     }
   }
 
-  @SuppressWarnings({"rawtypes", "unchecked"})
+  @SuppressWarnings({"rawtypes", "unchecked"}) // we loose the generic type information
   public static <REQUEST> void internalSetUrlTemplateExtractor(
       BiConsumer<HttpSpanNameExtractorBuilder<REQUEST>, Function<REQUEST, String>>
           urlTemplateExtractorSetter) {
@@ -76,7 +76,7 @@ public static <REQUEST, RESPONSE> void addOperationListenerAttributesExtractor(
     }
   }
 
-  @SuppressWarnings({"rawtypes", "unchecked"})
+  @SuppressWarnings({"rawtypes", "unchecked"}) // we loose the generic type information
   public static <REQUEST, RESPONSE> void internalAddOperationListenerAttributesExtractor(
       BiConsumer<
               InstrumenterBuilder<REQUEST, RESPONSE>,

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/InstrumenterContext.java

@@ -20,26 +20,25 @@
  * at any time.
  */
 public final class InstrumenterContext {
-  private static final ThreadLocal<InstrumenterContext> instrumenterContext =
-      new ThreadLocal<InstrumenterContext>() {
-        @Override
-        protected InstrumenterContext initialValue() {
-          return new InstrumenterContext();
-        }
-      };
+  private static final ThreadLocal<InstrumenterContext> instrumenterContext = new ThreadLocal<>();
 
   private final Map<String, Object> map = new HashMap<>();
 
   private InstrumenterContext() {}
 
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings("unchecked") // we expect the caller to use the same type for a given key
   public static <T> T computeIfAbsent(String key, Function<String, T> function) {
     return (T) get().computeIfAbsent(key, function);
   }
 
   // visible for testing
   static Map<String, Object> get() {
-    return instrumenterContext.get().map;
+    InstrumenterContext context = instrumenterContext.get();
+    if (context == null) {
+      context = new InstrumenterContext();
+      instrumenterContext.set(context);
+    }
+    return context.map;
   }
 
   public static void reset() {

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/RuntimeVirtualFieldSupplier.java

@@ -51,6 +51,7 @@ private static final class CacheBasedVirtualFieldSupplier implements VirtualFiel
         ownerToFieldToImplementationMap = Cache.weak();
 
     @Override
+    // storing VirtualField instances in a map looses the generic types
     @SuppressWarnings("unchecked")
     public <U extends T, V extends F, T, F> VirtualField<U, V> find(
         Class<T> type, Class<F> fieldType) {

instrumentation-api/src/main/java/io/opentelemetry/instrumentation/api/internal/ServiceLoaderUtil.java

@@ -18,6 +18,7 @@ public final class ServiceLoaderUtil {
 
   private ServiceLoaderUtil() {}
 
+  // we loose the generic type information because of using the loader function
   @SuppressWarnings("unchecked")
   public static <T> Iterable<T> load(Class<T> clazz) {
     return (Iterable<T>) loadFunction.apply(clazz);