Update Javadoc and exception message as per review comment

Author: ennuite

flight/flight-core/src/main/java/org/apache/arrow/flight/FlightClient.java

@@ -822,7 +822,13 @@ public Builder verifyServer(boolean verifyServer) {
       return this;
     }
 
-    /** Create the client from this builder. */
+    /**
+     * Create the client from this builder.
+     *
+     * @throws IllegalArgumentException if the location uses a TCP-based scheme ({@code grpc},
+     *     {@code grpc+tcp}, {@code grpc+tls}) and the location contains no port, or a port outside
+     *     the range [1, 65535].
+     */
     public FlightClient build() {
       final NettyChannelBuilder channelBuilder = builder.build();
       return new FlightClient(builder.allocator(), channelBuilder.build(), builder.middleware());

flight/flight-core/src/main/java/org/apache/arrow/flight/grpc/NettyClientBuilder.java

@@ -130,7 +130,13 @@ public NettyClientBuilder verifyServer(boolean verifyServer) {
     return this;
   }
 
-  /** Create the client from this builder. */
+  /**
+   * Create the client from this builder.
+   *
+   * @throws IllegalArgumentException if the URI uses a TCP-based scheme ({@code grpc}, {@code
+   *     grpc+tcp}, {@code grpc+tls}) and the URI contains no port, or a port outside the range [1,
+   *     65535].
+   */
   public NettyChannelBuilder build() {
     final NettyChannelBuilder builder;
 
@@ -140,6 +146,10 @@ public NettyChannelBuilder build() {
       case LocationSchemes.GRPC_TLS:
         {
           final int port = location.getUri().getPort();
+          if (port == -1) {
+            throw new IllegalArgumentException(
+                "No port specified in location URI: " + location.getUri());
+          }
           if (port < 1 || port > 65535) {
             throw new IllegalArgumentException(
                 "Invalid port " + port + ": must be between 1 and 65535.");