JVMCBC-1588 Fix parsing connection string where parameter value is URI

Motivation
----------
With the upcoming application telemetry feature,
we can expect users to specify the telemetry endpoint
with a connection string like this (note absent scheme):

   127.0.0.1?app_telemetry_endpoint=ws://example.com

When the scheme is omitted as in this example,
and there's a parameter value that contains a URI,
the connection string parser erroneously treats
everything before "://" as the connection string scheme.
This fails.

Modifications
-------------
Adjust the connection string scheme regex to disallow
question marks.

Rejected Alternatives
---------------------
RFC 2396 defines URI scheme as:

    scheme = alpha *( alpha | digit | "+" | "-" | "." )

where alpha is [a-zA-Z] and digit is [0-9].

By that definition, a strict Java regex for our scheme
would be:

  "((?<scheme>\\p{Alpha}[\\p{Alnum}+.-]*?)://)?"

but that seemed needlessly pedantic for our purposes.

Change-Id: Iafed4cec5cde5ba00ea607b844b3c941b49748cd
Reviewed-on: https://review.couchbase.org/c/couchbase-jvm-clients/+/221172
Tested-by: Build Bot <[email protected]>
Reviewed-by: Michael Reiche <[email protected]>

Author: dnault

core-io/src/main/java/com/couchbase/client/core/util/ConnectionString.java

@@ -49,7 +49,7 @@ public class ConnectionString {
   public static final String DEFAULT_SCHEME = "couchbase://";
 
   private static final Pattern connectionStringPattern = Pattern.compile(
-      "((?<scheme>.*?)://)?" +
+      "((?<scheme>[^?]*?)://)?" +
           "((?<user>.*?)@)?" +
           "(?<hosts>.*?)" +
           "(\\?(?<params>.*?))?"

core-io/src/test/java/com/couchbase/client/core/util/ConnectionStringTest.java

@@ -127,6 +127,22 @@ void shouldFailOnInvalidScheme() {
     assertThrows(CouchbaseException.class, () -> ConnectionString.create("invalid://"));
   }
 
+  @Test
+  void shouldParseParameterValueThatLooksLikeUri() {
+    ConnectionString cs = ConnectionString.create("couchbase://127.0.0.1?uri=ws://example.com");
+    assertEquals(COUCHBASE, cs.scheme());
+    assertEquals("127.0.0.1", cs.hosts().get(0).host());
+    assertEquals(mapOf("uri", "ws://example.com"), cs.params());
+  }
+
+  @Test
+  void shouldParseParameterValueThatLooksLikeUriEvenIfSchemeIsOmitted() {
+    ConnectionString cs = ConnectionString.create("127.0.0.1?uri=ws://example.com");
+    assertEquals(COUCHBASE, cs.scheme());
+    assertEquals("127.0.0.1", cs.hosts().get(0).host());
+    assertEquals(mapOf("uri", "ws://example.com"), cs.params());
+  }
+
   @Test
   void shouldParseHostList() {
     ConnectionString parsed = ConnectionString.create("couchbase://localhost");