add missing test

instrumentation-api/build.gradle.kts

@@ -20,6 +20,7 @@ dependencies {
   testImplementation(project(":testing-common"))
   testImplementation("io.opentelemetry:opentelemetry-sdk-metrics")
   testImplementation("io.opentelemetry:opentelemetry-sdk-testing")
+  testImplementation("org.junit-pioneer:junit-pioneer")
 
   jmhImplementation(project(":instrumentation-api-semconv"))
 }
@@ -35,4 +36,10 @@ tasks {
       isEnabled.set(false)
     }
   }
+
+  withType<Test>().configureEach {
+    // required on jdk17
+    jvmArgs("--add-opens=java.base/java.util=ALL-UNNAMED")
+    jvmArgs("-XX:+IgnoreUnrecognizedVMOptions")
+  }
 }

instrumentation-api/src/test/java/io/opentelemetry/instrumentation/api/internal/ConfigPropertiesUtilTest.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.instrumentation.api.internal;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.junitpioneer.jupiter.SetEnvironmentVariable;
+import org.junitpioneer.jupiter.SetSystemProperty;
+
+class ConfigPropertiesUtilTest {
+
+  @SetEnvironmentVariable(key = "TEST_PROPERTY_STRING", value = "env")
+  @SetSystemProperty(key = "test.property.string", value = "sys")
+  @Test
+  void getString_systemProperty() {
+    assertThat(ConfigPropertiesUtil.getString("test.property.string")).isEqualTo("sys");
+  }
+
+  @SetEnvironmentVariable(key = "TEST_PROPERTY_STRING", value = "env")
+  @Test
+  void getString_environmentVariable() {
+    assertThat(ConfigPropertiesUtil.getString("test.property.string")).isEqualTo("env");
+  }
+
+  @Test
+  void getString_none() {
+    assertThat(ConfigPropertiesUtil.getString("test.property.string")).isNull();
+  }
+
+  @SetEnvironmentVariable(key = "TEST_PROPERTY_INT", value = "12")
+  @SetSystemProperty(key = "test.property.int", value = "42")
+  @Test
+  void getInt_systemProperty() {
+    assertThat(ConfigPropertiesUtil.getInt("test.property.int", -1)).isEqualTo(42);
+  }
+
+  @SetEnvironmentVariable(key = "TEST_PROPERTY_INT", value = "12")
+  @Test
+  void getInt_environmentVariable() {
+    assertThat(ConfigPropertiesUtil.getInt("test.property.int", -1)).isEqualTo(12);
+  }
+
+  @Test
+  void getInt_none() {
+    assertThat(ConfigPropertiesUtil.getInt("test.property.int", -1)).isEqualTo(-1);
+  }
+
+  @SetSystemProperty(key = "test.property.int", value = "not a number")
+  @Test
+  void getInt_invalidNumber() {
+    assertThat(ConfigPropertiesUtil.getInt("test.property.int", -1)).isEqualTo(-1);
+  }
+
+  @SetEnvironmentVariable(key = "TEST_PROPERTY_BOOLEAN", value = "false")
+  @SetSystemProperty(key = "test.property.boolean", value = "true")
+  @Test
+  void getBoolean_systemProperty() {
+    assertThat(ConfigPropertiesUtil.getBoolean("test.property.boolean", false)).isTrue();
+  }
+
+  @SetEnvironmentVariable(key = "TEST_PROPERTY_BOOLEAN", value = "true")
+  @Test
+  void getBoolean_environmentVariable() {
+    assertThat(ConfigPropertiesUtil.getBoolean("test.property.boolean", false)).isTrue();
+  }
+
+  @Test
+  void getBoolean_none() {
+    assertThat(ConfigPropertiesUtil.getBoolean("test.property.boolean", false)).isFalse();
+  }
+}