fix test

Author: rahul2393

google-cloud-spanner/src/main/java/com/google/cloud/spanner/spi/v1/KeyRecipe.java

@@ -568,6 +568,22 @@ private static long[] parseUuid(String uuid) {
     } else if (uuid.endsWith("}")) {
       throw new IllegalArgumentException("Invalid UUID string: " + originalUuid);
     }
+    if (uuid.length() != 36
+        || uuid.charAt(8) != '-'
+        || uuid.charAt(13) != '-'
+        || uuid.charAt(18) != '-'
+        || uuid.charAt(23) != '-') {
+      throw new IllegalArgumentException("Invalid UUID string: " + originalUuid);
+    }
+    for (int i = 0; i < uuid.length(); i++) {
+      if (i == 8 || i == 13 || i == 18 || i == 23) {
+        continue;
+      }
+      char c = uuid.charAt(i);
+      if (!isHexChar(c)) {
+        throw new IllegalArgumentException("Invalid UUID string: " + originalUuid);
+      }
+    }
     try {
       UUID parsed = UUID.fromString(uuid);
       return new long[] {parsed.getMostSignificantBits(), parsed.getLeastSignificantBits()};
@@ -576,6 +592,12 @@ private static long[] parseUuid(String uuid) {
     }
   }
 
+  private static boolean isHexChar(char c) {
+    return (c >= '0' && c <= '9')
+        || (c >= 'a' && c <= 'f')
+        || (c >= 'A' && c <= 'F');
+  }
+
   private TargetRange encodeKeyInternal(
       BiFunction<Integer, String, Value> valueFinder, KeyType keyType) {
     UnsynchronizedByteArrayOutputStream ssKey = new UnsynchronizedByteArrayOutputStream();