[#1881] Improvement: ConfigConstants.java updated as class and is not…

… an interface (#2299)

### What changes were proposed in this pull request?

  - ConfigConstants updated as class and is not an interface

### Why are the changes needed?

  - Fix: #1881

### Does this PR introduce any user-facing change?

 - No

### How was this patch tested?

 - ./gradlew build

common/src/main/java/com/datastrato/gravitino/config/ConfigConstants.java

@@ -6,27 +6,30 @@
 package com.datastrato.gravitino.config;
 
 /** Constants used for configuration. */
-public interface ConfigConstants {
+public final class ConfigConstants {
+
+  private ConfigConstants() {}
 
   /** The value of messages used to indicate that the configuration is not set. */
-  String NOT_BLANK_ERROR_MSG = "The value can't be blank";
+  public static final String NOT_BLANK_ERROR_MSG = "The value can't be blank";
 
   /** The value of messages used to indicate that the configuration should be a positive number. */
-  String POSITIVE_NUMBER_ERROR_MSG = "The value must be a positive number";
+  public static final String POSITIVE_NUMBER_ERROR_MSG = "The value must be a positive number";
 
   /**
    * The value of messages used to indicate that the configuration should be a non-negative number.
    */
-  String NON_NEGATIVE_NUMBER_ERROR_MSG = "The value must be a non-negative number";
+  public static final String NON_NEGATIVE_NUMBER_ERROR_MSG =
+      "The value must be a non-negative number";
 
   /** The version number for the 0.1.0 release. */
-  String VERSION_0_1_0 = "0.1.0";
+  public static final String VERSION_0_1_0 = "0.1.0";
   /** The version number for the 0.2.0 release. */
-  String VERSION_0_2_0 = "0.2.0";
+  public static final String VERSION_0_2_0 = "0.2.0";
   /** The version number for the 0.3.0 release. */
-  String VERSION_0_3_0 = "0.3.0";
+  public static final String VERSION_0_3_0 = "0.3.0";
   /** The version number for the 0.4.0 release. */
-  String VERSION_0_4_0 = "0.4.0";
+  public static final String VERSION_0_4_0 = "0.4.0";
   /** The version number for the 0.5.0 release. */
-  String VERSION_0_5_0 = "0.5.0";
+  public static final String VERSION_0_5_0 = "0.5.0";
 }