[Java] Add a message showing when there are no drivers on $PATH

This changes the Require to handle a unique message which can help
guide users on how to fix the issue that they are hitting.

java/client/src/org/openqa/selenium/internal/Require.java

@@ -138,17 +138,24 @@ public static int nonNegative(String argName, Integer number) {
     }
     return number;
   }
-
-  public static int positive(String argName, Integer number) {
+  public static int positive(String argName, Integer number, String message) {
     if (number == null) {
       throw new IllegalArgumentException(argName + " must be set");
     }
     if (number <= 0) {
-      throw new IllegalArgumentException(argName + " must be greater than 0");
+      if (message == null) {
+        throw new IllegalArgumentException(argName + " must be greater than 0");
+      } else {
+        throw new IllegalArgumentException(message);
+      }
     }
     return number;
   }
 
+  public static int positive(String argName, Integer number) {
+    return positive(argName, number, null);
+  }
+
   public static IntChecker argument(String argName, Integer number) {
     return new IntChecker(argName, number);
   }

java/client/test/org/openqa/selenium/RequireTest.java

@@ -145,6 +145,13 @@ public void canCheckIntegerArgument() {
     assertThat(Require.positive("Timeout", 5)).isEqualTo(5);
   }
 
+  @Test
+  public void canCheckIntegersWithMessages() {
+    assertThatExceptionOfType(IllegalArgumentException.class)
+        .isThrownBy(() -> Require.positive("Timeout", 0, "Message should only be this"))
+        .withMessage("Message should only be this");
+  }
+
   @Test
   public void canCheckIntegerArgumentWithCheckerObject() {
     assertThatExceptionOfType(IllegalArgumentException.class)

java/server/src/org/openqa/selenium/grid/data/NodeStatus.java

@@ -51,7 +51,9 @@ public NodeStatus(
       Secret registrationSecret) {
     this.nodeId = Require.nonNull("Node id", nodeId);
     this.externalUri = Require.nonNull("URI", externalUri);
-    this.maxSessionCount = Require.positive("Max session count", maxSessionCount);
+    this.maxSessionCount = Require.positive("Max session count",
+        maxSessionCount,
+"Make sure that a driver is available on $PATH");
     this.slots = ImmutableSet.copyOf(Require.nonNull("Slots", slots));
     this.availability = Require.nonNull("Availability", availability);
     this.registrationSecret = registrationSecret;