HBASE-23904 Procedure updating meta and Master shutdown are incompatible: CODE-BUG

Restore behavior from before HBASE-21789 (hbase-2.2.0) where we convert
all exceptions to IOEs, even RuntimeExceptions. Actual fix is this change (in case
obscured by doc and lambda simplification):

     } catch (Throwable e) {
-      Throwables.propagateIfPossible(e, IOException.class);
+      // Throw if an IOE else wrap in an IOE EVEN IF IT IS a RuntimeException (e.g.
+      // a RejectedExecutionException because the hosting exception is shutting down.
+      // This is old behavior worth reexamining. Procedures doing merge or split
+      // currently don't handle RuntimeExceptions coming up out of meta table edits.
+      // Would have to work on this at least. See HBASE-23904.
+      Throwables.throwIfInstanceOf(e, IOException.class);

hbase-client/src/main/java/org/apache/hadoop/hbase/MetaTableAccessor.java

@@ -233,8 +233,7 @@ public class MetaTableAccessor {
    * @return An {@link Table} for <code>hbase:meta</code>
    * @throws NullPointerException if {@code connection} is {@code null}
    */
-  public static Table getMetaHTable(final Connection connection)
+  public static Table getMetaHTable(final Connection connection) throws IOException {
-  throws IOException {
     // We used to pass whole CatalogTracker in here, now we just pass in Connection
     Objects.requireNonNull(connection, "Connection cannot be null");
     if (connection.isClosed()) {
@@ -1674,16 +1673,15 @@ public class MetaTableAccessor {
   }
 
   /**
-   * Performs an atomic multi-mutate operation against the given table.
+   * Performs an atomic multi-mutate operation against the given table. Used by the likes of
+   * merge and split as these want to make atomic mutations across multiple rows.
+   * @throws IOException even if we encounter a RuntimeException, we'll still wrap it in an IOE.
    */
-  private static void multiMutate(final Table table, byte[] row, final List<Mutation> mutations)
+  @VisibleForTesting
+  static void multiMutate(final Table table, byte[] row, final List<Mutation> mutations)
       throws IOException {
     debugLogMutations(mutations);
-    Batch.Call<MultiRowMutationService, MutateRowsResponse> callable =
+    Batch.Call<MultiRowMutationService, MutateRowsResponse> callable = instance -> {
-      new Batch.Call<MultiRowMutationService, MutateRowsResponse>() {
-
-        @Override
-        public MutateRowsResponse call(MultiRowMutationService instance) throws IOException {
       MutateRowsRequest.Builder builder = MutateRowsRequest.newBuilder();
       for (Mutation mutation : mutations) {
         if (mutation instanceof Put) {
@@ -1706,12 +1704,16 @@ public class MetaTableAccessor {
         throw controller.getFailedOn();
       }
       return resp;
-        }
     };
     try {
       table.coprocessorService(MultiRowMutationService.class, row, row, callable);
     } catch (Throwable e) {
-      Throwables.propagateIfPossible(e, IOException.class);
+      // Throw if an IOE else wrap in an IOE EVEN IF IT IS a RuntimeException (e.g.
+      // a RejectedExecutionException because the hosting exception is shutting down.
+      // This is old behavior worth reexamining. Procedures doing merge or split
+      // currently don't handle RuntimeExceptions coming up out of meta table edits.
+      // Would have to work on this at least. See HBASE-23904.
+      Throwables.throwIfInstanceOf(e, IOException.class);
       throw new IOException(e);
     }
   }