Update to new errorprone checks

Author: trask

instrumentation/servlet/servlet-3.0/javaagent-unit-tests/src/test/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/snippet/TestUtil.java

@@ -11,6 +11,7 @@
 import java.nio.charset.StandardCharsets;
 
 public class TestUtil {
+
   public static String readFile(String resourceName) throws IOException {
     InputStream in =
         SnippetInjectingResponseWrapperTest.class
@@ -24,4 +25,6 @@ public static String readFile(String resourceName) throws IOException {
     }
     return result.toString(StandardCharsets.UTF_8.name());
   }
+
+  private TestUtil() {}
 }

instrumentation/servlet/servlet-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/snippet/Injection.java

@@ -9,6 +9,7 @@
 import javax.servlet.ServletOutputStream;
 
 public class Injection {
+
   private static final VirtualField<ServletOutputStream, InjectionState> virtualField =
       VirtualField.find(ServletOutputStream.class, InjectionState.class);
 
@@ -28,4 +29,6 @@ public static void initializeInjectionStateIfNeeded(
   public static InjectionState getInjectionState(ServletOutputStream servletOutputStream) {
     return virtualField.get(servletOutputStream);
   }
+
+  private Injection() {}
 }

instrumentation/servlet/servlet-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/servlet/v3_0/snippet/ServletOutputStreamInjectionHelper.java

@@ -14,6 +14,7 @@
 import javax.servlet.ServletOutputStream;
 
 public class ServletOutputStreamInjectionHelper {
+
   private static final Logger logger =
       Logger.getLogger(ServletOutputStreamInjectionHelper.class.getName());
 
@@ -84,4 +85,6 @@ public static boolean handleWrite(InjectionState state, ServletOutputStream out,
     out.write(snippetBytes);
     return true;
   }
+
+  private ServletOutputStreamInjectionHelper() {}
 }