Make spotless work

In this commit, we are making spotless work, as I found out that
spotless is not being run in the upstream for benchmark-overhead. To
achive this, I've added a license file to `scripts` and updated
build.gradle.kts to reference it. Then I ran spotlessApply to bring the
code up to expectations. In future commits, we will automatically run
spotless to ensure code is up to standards on every commit.

performance-tests/build.gradle.kts

@@ -6,7 +6,7 @@ plugins {
 spotless {
   java {
     googleJavaFormat()
-    licenseHeaderFile(rootProject.file("../buildscripts/spotless.license.java"), "(package|import|public)")
+    licenseHeaderFile(rootProject.file("../scripts/spotless.license.java"), "(package|import|public)")
     target("src/**/*.java")
   }
 }

performance-tests/src/test/java/io/opentelemetry/OverheadTests.java

@@ -123,16 +123,27 @@ private void startRecording(Agent agent, GenericContainer<?> petclinic) throws E
     petclinic.execInContainer(command);
   }
 
-  private void doWarmupPhase(TestConfig testConfig, GenericContainer<?> petclinic) throws IOException, InterruptedException {
-    System.out.println("Performing startup warming phase for " + testConfig.getWarmupSeconds() + " seconds...");
+  private void doWarmupPhase(TestConfig testConfig, GenericContainer<?> petclinic)
+      throws IOException, InterruptedException {
+    System.out.println(
+        "Performing startup warming phase for " + testConfig.getWarmupSeconds() + " seconds...");
 
     // excluding the JFR recording from the warmup causes strange inconsistencies in the results
     System.out.println("Starting disposable JFR warmup recording...");
-    String[] startCommand = {"jcmd", "1", "JFR.start", "settings=/app/overhead.jfc", "dumponexit=true", "name=warmup", "filename=warmup.jfr"};
+    String[] startCommand = {
+      "jcmd",
+      "1",
+      "JFR.start",
+      "settings=/app/overhead.jfc",
+      "dumponexit=true",
+      "name=warmup",
+      "filename=warmup.jfr"
+    };
     petclinic.execInContainer(startCommand);
 
-    long deadline = System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(testConfig.getWarmupSeconds());
-    while(System.currentTimeMillis() < deadline) {
+    long deadline =
+        System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(testConfig.getWarmupSeconds());
+    while (System.currentTimeMillis() < deadline) {
       GenericContainer<?> k6 =
           new GenericContainer<>(DockerImageName.parse("loadimpact/k6"))
               .withNetwork(NETWORK)

performance-tests/src/test/java/io/opentelemetry/util/NamingConventions.java

@@ -11,12 +11,16 @@ public class NamingConventions {
   public final NamingConvention container = new NamingConvention("/results");
   public final NamingConvention local = new NamingConvention(".");
 
-  /** @return Root path for the local naming convention (where results are output) */
+  /**
+   * @return Root path for the local naming convention (where results are output)
+   */
   public String localResults() {
     return local.root();
   }
 
-  /** @return Root path for the container naming convention (where results are output) */
+  /**
+   * @return Root path for the container naming convention (where results are output)
+   */
   public String containerResults() {
     return container.root();
   }

scripts/spotless.license.java

@@ -0,0 +1,5 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+