Clean up javadoc warnings in OpenCensusUtils (#714)

* Clean up javadoc warnings

* Remove redundant wording

Author: chingor13

google-http-client/src/main/java/com/google/api/client/http/HttpRequest.java

@@ -1124,7 +1124,7 @@ public HttpResponse call() throws Exception {
   /**
    * {@link Beta} <br>
    * Executes this request asynchronously using {@link #executeAsync(Executor)} in a single separate
-   * thread using {@link Executors#newFixedThreadPool(1)}.
+   * thread using {@link Executors#newFixedThreadPool(int)}.
    *
    * @return A future for accessing the results of the asynchronous request.
    * @since 1.13

google-http-client/src/main/java/com/google/api/client/http/OpenCensusUtils.java

@@ -81,7 +81,7 @@ public static void setPropagationTextFormat(@Nullable TextFormat textFormat) {
   }
 
   /**
-   * Sets the {@link TextFormat.Setter} used in context propagation.
+   * Sets the {@link io.opencensus.trace.propagation.TextFormat.Setter} used in context propagation.
    *
    * <p>This API allows users of google-http-client to specify other text format setter, or disable
    * context propagation by setting it to {@code null}. It should be used along with {@link

google-http-client/src/main/java/com/google/api/client/json/JsonParser.java

@@ -53,7 +53,7 @@
  * <p>
  *
  * <p>If a JSON map is encountered while using a destination class of type Map, then an {@link
- * ArrayMap} is used by default for the parsed values.
+ * java.util.ArrayMap} is used by default for the parsed values.
  *
  * @since 1.3
  * @author Yaniv Inbar