[BUG] NPE when trying to connect to the database using invalid URI

[yagudin10]

Describe the bug

The Databricks JDBC driver throws a NullPointerException when connecting with an invalid JDBC URI that does not contain the required connection parameters (e.g. httpPath).

To Reproduce

1. Use an invalid Databricks JDBC URI, for example (e.g. jdbc:databricks://localhost:8080)
2. Attempt to connect to the database using the URI

Sample code:

        String databricksUrl = "jdbc:databricks://localhost:8080";
        Properties properties = new Properties();
        Driver driver = DriverManager.getDriver(databricksUrl);
        try (Connection connection = driver.connect(databricksUrl, properties)) {
            System.out.println("Connected to Databricks successfully!");
        }

Expected behavior
The driver should throw a meaningful exception indicating that the JDBC URI is invalid or missing required connection parameters.

Client side logs

Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.lang.CharSequence.length()" because "this.text" is null
	at java.base/java.util.regex.Matcher.getTextLength(Matcher.java:1769)
	at java.base/java.util.regex.Matcher.reset(Matcher.java:415)
	at java.base/java.util.regex.Matcher.<init>(Matcher.java:252)
	at java.base/java.util.regex.Pattern.matcher(Pattern.java:1134)
	at com.databricks.jdbc.api.impl.DatabricksConnectionContext.buildCompute(DatabricksConnectionContext.java:1324)
	at com.databricks.jdbc.api.impl.DatabricksConnectionContext.<init>(DatabricksConnectionContext.java:76)
	at com.databricks.jdbc.api.impl.DatabricksConnectionContext.parse(DatabricksConnectionContext.java:191)
	at com.databricks.jdbc.api.impl.DatabricksConnectionContextFactory.create(DatabricksConnectionContextFactory.java:20)
	at com.databricks.client.jdbc.Driver.connect(Driver.java:56)

Client Environment:

• OS: Mac OS Sonoma 14.3.1
• Java version: 17
• Java vendor: OpenJDK
• Driver Version: 3.4.2

[adityaanikam]

Confirmed the exact crash: getHttpPath() returns a plain getParameter() lookup, null when the URL doesn't set httpPath, and buildCompute() passes that straight into HTTP_WAREHOUSE_PATH_PATTERN.matcher(httpPath) with nothing checking for null first. Matches your stack trace exactly, Matcher's constructor is where a null CharSequence blows up.

There's already a nullOrEmptyString() helper a few lines above in the same file, unused at this call site, so there's a house pattern to follow. The open question is really where the guard belongs and what it should raise, right at buildCompute(), earlier at URL parsing so the error surfaces before any parameter dependent logic runs, or something else, plus whether a plain IllegalArgumentException is the right exception type here or if the driver has its own convention for errors meant for users. Which direction fits how the rest of the driver handles missing required parameters?