Make the javadoc descriptions of various Exception implementations parallel one another better (#1841)

Author: DavidMGross

src/main/java/rx/exceptions/CompositeException.java

@@ -26,8 +26,8 @@
 import java.util.Set;
 
 /**
- * An Exception that is a composite of one or more other Exceptions. A {@code CompositeException} does not
- * modify the structure of any exception it wraps, but at print-time it iterates through the list of
+ * Represents an exception that is a composite of one or more other exceptions. A {@code CompositeException}
+ * does not modify the structure of any exception it wraps, but at print-time it iterates through the list of
  * Throwables contained in the composit in order to print them all.
  *
  * Its invariant is to contain an immutable, ordered (by insertion order), unique list of non-composite

src/main/java/rx/exceptions/Exceptions.java

@@ -28,7 +28,8 @@ private Exceptions() {
 
     /**
      * @warn javadoc missing
-     * @return
+     * @return because {@code propagate} itself throws an exception or error, this is a sort of phantom return
+     *         value; {@code propagate} does not actually return anything
      */
     public static RuntimeException propagate(Throwable t) {
         /*

src/main/java/rx/exceptions/MissingBackpressureException.java

@@ -16,7 +16,7 @@
 package rx.exceptions;
 
 /**
- * {@code MissingBackpressureException} indicates that a Subscriber or operator attempted to apply reactive pull
+ * Represents an exception that indicates that a Subscriber or operator attempted to apply reactive pull
  * backpressure to an Observable that does not implement it.
  * <p>
  * If an Observable has not been written to support reactive pull backpressure (such support is not a

src/main/java/rx/exceptions/OnErrorFailedException.java

@@ -18,7 +18,7 @@
 import rx.Subscriber;
 
 /**
- * Used to re-throw errors thrown from {@link Subscriber#onError(Throwable)}.
+ * Represents an exception used to re-throw errors thrown from {@link Subscriber#onError(Throwable)}.
  * <p>
  * @see <a href="https://github.com/ReactiveX/RxJava/issues/969">RxJava issue #969</a>
  */

src/main/java/rx/exceptions/OnErrorNotImplementedException.java

@@ -18,7 +18,8 @@
 import rx.Subscriber;
 
 /**
- * Used to re-throw {@link Subscriber#onError(Throwable)} when an implementation doesn't exist.
+ * Represents an exception used to re-throw {@link Subscriber#onError(Throwable)} when an implementation doesn't
+ * exist.
  * <p>
  * Rx Design Guidelines 5.2:
  * <blockquote><p>