{*Graph, Network}.java: change documentation of allowsSelfLoops() and…

… allowsParallelEdges() to correct the type of exception that is thrown when one attempts to modify them in a way that the constraint prevents (e.g., adding a self-loop to a graph that doesn't allow them).

Technically this is a contract change, but in fact the implementations were already throwing IllegalArgumentException, so in practice anyone that was depending on that documentation being accurate (by, say, catching UnsupportedOperationException) was already in trouble, so IMO we should just make this change without trying to worry about backward compatibility; this is just a bug fix.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=147933338

guava/src/com/google/common/graph/BaseGraph.java

@@ -51,7 +51,7 @@ interface BaseGraph<N> extends SuccessorGraph<N>, PredecessorGraph<N> {
   /**
    * Returns true if this graph allows self-loops (edges that connect a node to itself). Attempting
    * to add a self-loop to a graph that does not allow them will throw an {@link
-   * UnsupportedOperationException}.
+   * IllegalArgumentException}.
    */
   boolean allowsSelfLoops();
 

guava/src/com/google/common/graph/Network.java

@@ -139,14 +139,14 @@ public interface Network<N, E> extends SuccessorGraph<N>, PredecessorGraph<N> {
 
   /**
    * Returns true if this network allows parallel edges. Attempting to add a parallel edge to a
-   * network that does not allow them will throw an {@link UnsupportedOperationException}.
+   * network that does not allow them will throw an {@link IllegalArgumentException}.
    */
   boolean allowsParallelEdges();
 
   /**
    * Returns true if this network allows self-loops (edges that connect a node to itself).
    * Attempting to add a self-loop to a network that does not allow them will throw an {@link
-   * UnsupportedOperationException}.
+   * IllegalArgumentException}.
    */
   boolean allowsSelfLoops();