Updated CLI token source parseExpiry method to account for different time format (#116)

## Changes
<!-- Summary of your changes that are easy to understand -->
Add functionality to check for different date format for expiry parsing
in CLI token source. Also add pattern matching for flexibility between
different java versions

## Tests
<!-- How is this tested? -->
Added unit tests, since `LocalDateTime` support upto nano second
precision -- tested for less and more digits as well.

Author: tanmay-db

databricks-sdk-java/src/main/java/com/databricks/sdk/core/CliTokenSource.java

@@ -37,10 +37,15 @@ public CliTokenSource(
     this.getAllEnv = getAllEnv;
   }
 
-  private static LocalDateTime parseExpiry(String expiry) {
+  static LocalDateTime parseExpiry(String expiry) {
+    String multiplePrecisionPattern =
+        "[SSSSSSSSS][SSSSSSSS][SSSSSSS][SSSSSS][SSSSS][SSSS][SSS][SS][S]";
     List<String> datePatterns =
         Arrays.asList(
-            "yyyy-MM-dd HH:mm:ss.SSSSSS", "yyyy-MM-dd HH:mm:ss", "yyyy-MM-dd'T'HH:mm:ss.SSSSSSXXX");
+            "yyyy-MM-dd HH:mm:ss",
+            "yyyy-MM-dd HH:mm:ss." + multiplePrecisionPattern,
+            "yyyy-MM-dd'T'HH:mm:ss." + multiplePrecisionPattern + "XXX",
+            "yyyy-MM-dd'T'HH:mm:ss." + multiplePrecisionPattern + "'Z'");
     DateTimeParseException lastException = null;
     for (String pattern : datePatterns) {
       try {

databricks-sdk-java/src/test/java/com/databricks/sdk/core/CliTokenSourceTest.java

@@ -0,0 +1,37 @@
+package com.databricks.sdk.core;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.time.LocalDateTime;
+import java.time.format.DateTimeParseException;
+import org.junit.jupiter.api.Test;
+
+public class CliTokenSourceTest {
+
+  @Test
+  public void testParseExpiryWithoutTruncate() {
+    LocalDateTime parsedDateTime = CliTokenSource.parseExpiry("2023-07-17T09:02:22.330612218Z");
+    assertEquals(LocalDateTime.of(2023, 7, 17, 9, 2, 22, 330612218), parsedDateTime);
+  }
+
+  @Test
+  public void testParseExpiryWithTruncate() {
+    LocalDateTime parsedDateTime = CliTokenSource.parseExpiry("2023-07-17T09:02:22.33061221Z");
+    assertEquals(LocalDateTime.of(2023, 7, 17, 9, 2, 22, 330612210), parsedDateTime);
+  }
+
+  @Test
+  public void testParseExpiryWithTruncateAndLessNanoSecondDigits() {
+    LocalDateTime parsedDateTime = CliTokenSource.parseExpiry("2023-07-17T09:02:22.330612Z");
+    assertEquals(LocalDateTime.of(2023, 7, 17, 9, 2, 22, 330612000), parsedDateTime);
+  }
+
+  @Test
+  public void testParseExpiryWithMoreThanNineNanoSecondDigits() {
+    try {
+      CliTokenSource.parseExpiry("2023-07-17T09:02:22.33061221987Z");
+    } catch (DateTimeParseException e) {
+      assert (e.getMessage().contains("could not be parsed"));
+    }
+  }
+}