Merge PR #273: Update noop-api module to follow style guide

Author: trask

noop-api/src/main/java/io/opentelemetry/contrib/noopapi/NoopContextStorageProvider.java

@@ -15,7 +15,7 @@
 /**
  * A {@link ContextStorageProvider} that returns a {@link ContextStorage} which is completely no-op.
  */
-public class NoopContextStorageProvider implements ContextStorageProvider {
+public final class NoopContextStorageProvider implements ContextStorageProvider {
 
   /** Returns a no-op context storage. */
   @Override

noop-api/src/main/java/io/opentelemetry/contrib/noopapi/NoopOpenTelemetry.java

@@ -42,7 +42,7 @@
  * <p>The above will succeed both with the {@linkplain OpenTelemetry#noop() default implementation}
  * and this one, but with this implementation there will be no overhead at all.
  */
-public class NoopOpenTelemetry implements OpenTelemetry {
+public final class NoopOpenTelemetry implements OpenTelemetry {
 
   private static final OpenTelemetry INSTANCE = new NoopOpenTelemetry();
 

noop-api/src/test/java/io/opentelemetry/contrib/noopapi/NoopOpenTelemetryTest.java

@@ -5,6 +5,7 @@
 
 package io.opentelemetry.contrib.noopapi;
 
+import static java.util.concurrent.TimeUnit.DAYS;
 import static org.assertj.core.api.Assertions.assertThat;
 
 import io.opentelemetry.api.common.AttributeKey;
@@ -17,7 +18,6 @@
 import io.opentelemetry.api.trace.TraceState;
 import io.opentelemetry.context.Context;
 import io.opentelemetry.context.Scope;
-import java.util.concurrent.TimeUnit;
 import org.junit.jupiter.api.Test;
 
 class NoopOpenTelemetryTest {
@@ -61,7 +61,7 @@ void tracerNoOp() {
     span1.setAttribute("key", true);
     span1.setAttribute(AttributeKey.stringKey("key"), "value");
     span1.setSpanKind(SpanKind.CLIENT);
-    span1.setStartTimestamp(1, TimeUnit.DAYS);
+    span1.setStartTimestamp(1, DAYS);
 
     // No allocations
     assertThat(span1.startSpan()).isSameAs(Span.getInvalid());