Polishing.

Add missing assertions. Javadoc.

See gh-284.

spring-vault-core/src/main/java/org/springframework/vault/authentication/AwsEc2Authentication.java

@@ -74,7 +74,7 @@ public class AwsEc2Authentication implements ClientAuthentication,
 	/**
 	 * Create a new {@link AwsEc2Authentication} specifying
 	 * {@link AwsEc2AuthenticationOptions}, a Vault and an AWS-Metadata-specific
-	 * {@link RestOperations} .
+	 * {@link RestOperations}.
 	 *
 	 * @param options must not be {@literal null}.
 	 * @param vaultRestOperations must not be {@literal null}.

spring-vault-core/src/main/java/org/springframework/vault/authentication/AwsEc2AuthenticationOptions.java

@@ -151,13 +151,15 @@ public class AwsEc2AuthenticationOptions {
 		/**
 		 * Configure the Identity Document {@link URI}.
 		 *
-		 * @param identityDocumentUri must not be empty or {@literal null}.
+		 * @param identityDocumentUri must not be {@literal null}.
 		 * @return {@code this} {@link AwsEc2AuthenticationOptionsBuilder}.
 		 * @see #DEFAULT_PKCS7_IDENTITY_DOCUMENT_URI
 		 */
 		public AwsEc2AuthenticationOptionsBuilder identityDocumentUri(
 				URI identityDocumentUri) {
 
+			Assert.notNull(identityDocumentUri, "Identity document URI must not be null");
+
 			this.identityDocumentUri = identityDocumentUri;
 			return this;
 		}

spring-vault-core/src/main/java/org/springframework/vault/authentication/AwsIamAuthentication.java

@@ -83,7 +83,7 @@ public class AwsIamAuthentication implements ClientAuthentication {
 	/**
 	 * Create a new {@link AwsIamAuthentication} specifying
 	 * {@link AwsIamAuthenticationOptions}, a Vault and an AWS-Metadata-specific
-	 * {@link RestOperations} .
+	 * {@link RestOperations}.
 	 *
 	 * @param options must not be {@literal null}.
 	 * @param vaultRestOperations must not be {@literal null}.