ACCUMULO-4756 Small regex fixes for validating names

Fix a few small regex issues with namespace and table name validation.
This fix allows the default namespace to be specified in the
comma-separated list of namespaces, along with other namespaces.

Also apply minor regex cleanup by removing unnecessary parens, applying
constraints on the number of digits in a port for server:port, and
deduplicating the server regex for the case where it is optional.

Also apply previously uncommitted formatting changes.

server/monitor/src/main/java/org/apache/accumulo/monitor/rest/tables/TablesResource.java

@@ -213,7 +213,8 @@ public TablesList getTableWithNamespace(@PathParam("namespaces") @NotNull @Patte
    */
   @Path("{tableId}")
   @GET
-  public TabletServers getParticipatingTabletServers(@PathParam("tableId") @NotNull @Pattern(regexp = ALPHA_NUM_REGEX_TABLE_ID) String tableIdStr) throws Exception {
+  public TabletServers getParticipatingTabletServers(@PathParam("tableId") @NotNull @Pattern(regexp = ALPHA_NUM_REGEX_TABLE_ID) String tableIdStr)
+      throws Exception {
     Instance instance = Monitor.getContext().getInstance();
     Table.ID tableId = Table.ID.of(tableIdStr);
 

server/monitor/src/main/java/org/apache/accumulo/monitor/util/ParameterValidator.java

@@ -28,9 +28,13 @@ public interface ParameterValidator {
 
   String RESOURCE_REGEX = "(\\w|:)+";
 
-  String NAMESPACE_REGEX = "[*-]?|(\\w)+";
-  String NAMESPACE_LIST_REGEX = "[*-]?|(\\w+,?\\w*)+";
+  // asterisk or - or blank or a namespace name
+  String NAMESPACE_REGEX = "[*-]?|\\w+";
 
-  String SERVER_REGEX = "(\\w+([.-])*\\w*)+(:[0-9]+)*";
-  String SERVER_REGEX_BLANK_OK = "((\\w+([.-])*\\w*)+(:[0-9]+)*)*";
+  // asterisk or blank or a comma-separated list of - or namespace names (optional trailing comma)
+  String NAMESPACE_LIST_REGEX = "[*]?|([-]|\\w+)(,([-]|\\w+))*,?";
+
+  // host name and port
+  String SERVER_REGEX = "(\\w+[.-]*\\w*)+(:[0-9]{1,5})*";
+  String SERVER_REGEX_BLANK_OK = "(" + SERVER_REGEX + ")*";
 }