fix(config): Move ObjectMapper to internal YamlObjectMapper class

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/DeclarativeConfiguration.java

@@ -5,17 +5,15 @@
 
 package io.opentelemetry.sdk.extension.incubator.fileconfig;
 
-import com.fasterxml.jackson.annotation.JsonSetter;
-import com.fasterxml.jackson.annotation.Nulls;
 import com.fasterxml.jackson.core.type.TypeReference;
-import com.fasterxml.jackson.databind.ObjectMapper;
 import io.opentelemetry.api.incubator.config.DeclarativeConfigException;
 import io.opentelemetry.api.incubator.config.DeclarativeConfigProperties;
 import io.opentelemetry.common.ComponentLoader;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.autoconfigure.internal.SpiHelper;
 import io.opentelemetry.sdk.autoconfigure.spi.internal.AutoConfigureListener;
 import io.opentelemetry.sdk.autoconfigure.spi.internal.ComponentProvider;
+import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.YamlObjectMapper;
 import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.OpenTelemetryConfigurationModel;
 import io.opentelemetry.sdk.extension.incubator.fileconfig.internal.model.SamplerModel;
 import io.opentelemetry.sdk.internal.ExtendedOpenTelemetrySdk;
@@ -62,22 +60,6 @@ public final class DeclarativeConfiguration {
   private static final ComponentLoader DEFAULT_COMPONENT_LOADER =
       ComponentLoader.forClassLoader(DeclarativeConfigProperties.class.getClassLoader());
 
-  // Visible for testing
-  static final ObjectMapper MAPPER;
-
-  static {
-    MAPPER =
-        new ObjectMapper()
-            // Create empty object instances for keys which are present but have null values
-            .setDefaultSetterInfo(JsonSetter.Value.forValueNulls(Nulls.AS_EMPTY));
-    // Boxed primitives which are present but have null values should be set to null, rather than
-    // empty instances
-    MAPPER.configOverride(String.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
-    MAPPER.configOverride(Integer.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
-    MAPPER.configOverride(Double.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
-    MAPPER.configOverride(Boolean.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
-  }
-
   private DeclarativeConfiguration() {}
 
   /**
@@ -158,7 +140,8 @@ public static OpenTelemetryConfigurationModel parse(InputStream configuration) {
   static OpenTelemetryConfigurationModel parse(
       InputStream configuration, Map<String, String> environmentVariables) {
     Object yamlObj = loadYaml(configuration, environmentVariables);
-    return MAPPER.convertValue(yamlObj, OpenTelemetryConfigurationModel.class);
+    return YamlObjectMapper.getInstance()
+        .convertValue(yamlObj, OpenTelemetryConfigurationModel.class);
   }
 
   // Visible for testing
@@ -192,7 +175,8 @@ public static DeclarativeConfigProperties toConfigProperties(InputStream configu
   static DeclarativeConfigProperties toConfigProperties(
       Object model, ComponentLoader componentLoader) {
     Map<String, Object> configurationMap =
-        MAPPER.convertValue(model, new TypeReference<Map<String, Object>>() {});
+        YamlObjectMapper.getInstance()
+            .convertValue(model, new TypeReference<Map<String, Object>>() {});
     if (configurationMap == null) {
       configurationMap = Collections.emptyMap();
     }
@@ -213,8 +197,10 @@ public static Sampler createSampler(DeclarativeConfigProperties genericSamplerMo
     YamlDeclarativeConfigProperties yamlDeclarativeConfigProperties =
         requireYamlDeclarativeConfigProperties(genericSamplerModel);
     SamplerModel samplerModel =
-        MAPPER.convertValue(
-            DeclarativeConfigProperties.toMap(yamlDeclarativeConfigProperties), SamplerModel.class);
+        YamlObjectMapper.getInstance()
+            .convertValue(
+                DeclarativeConfigProperties.toMap(yamlDeclarativeConfigProperties),
+                SamplerModel.class);
     return createAndMaybeCleanup(
         SamplerFactory.getInstance(),
         DeclarativeConfigContext.create(yamlDeclarativeConfigProperties.getComponentLoader()),

sdk-extensions/incubator/src/main/java/io/opentelemetry/sdk/extension/incubator/fileconfig/internal/YamlObjectMapper.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.sdk.extension.incubator.fileconfig.internal;
+
+import com.fasterxml.jackson.annotation.JsonSetter;
+import com.fasterxml.jackson.annotation.Nulls;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+/**
+ * Provides a configured {@link ObjectMapper} for YAML declarative configuration parsing.
+ *
+ * <p>This class is internal and is hence not for public use. Its APIs are unstable and can change
+ * at any time.
+ */
+public final class YamlObjectMapper {
+
+  private static final ObjectMapper INSTANCE;
+
+  static {
+    INSTANCE =
+        new ObjectMapper()
+            // Create empty object instances for keys which are present but have null values
+            .setDefaultSetterInfo(JsonSetter.Value.forValueNulls(Nulls.AS_EMPTY));
+    // Boxed primitives which are present but have null values should be set to null, rather than
+    // empty instances
+    INSTANCE.configOverride(String.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
+    INSTANCE.configOverride(Integer.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
+    INSTANCE.configOverride(Double.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
+    INSTANCE.configOverride(Boolean.class).setSetterInfo(JsonSetter.Value.forValueNulls(Nulls.SET));
+  }
+
+  private YamlObjectMapper() {}
+
+  /**
+   * Returns the configured {@link ObjectMapper} instance for parsing YAML declarative
+   * configuration.
+   *
+   * @return the configured ObjectMapper
+   */
+  public static ObjectMapper getInstance() {
+    return INSTANCE;
+  }
+}