Fix typo

Closes gh-1545

Author: MottoX

spring-tx/src/main/java/org/springframework/transaction/support/AbstractPlatformTransactionManager.java

@@ -206,7 +206,7 @@ public final boolean isNestedTransactionAllowed() {
 	 * Set whether existing transactions should be validated before participating
 	 * in them.
 	 * <p>When participating in an existing transaction (e.g. with
-	 * PROPAGATION_REQUIRES or PROPAGATION_SUPPORTS encountering an existing
+	 * PROPAGATION_REQUIRED or PROPAGATION_SUPPORTS encountering an existing
 	 * transaction), this outer transaction's characteristics will apply even
 	 * to the inner transaction scope. Validation will detect incompatible
 	 * isolation level and read-only settings on the inner transaction definition
@@ -231,7 +231,7 @@ public final boolean isValidateExistingTransaction() {
 	 * Set whether to globally mark an existing transaction as rollback-only
 	 * after a participating transaction failed.
 	 * <p>Default is "true": If a participating transaction (e.g. with
-	 * PROPAGATION_REQUIRES or PROPAGATION_SUPPORTS encountering an existing
+	 * PROPAGATION_REQUIRED or PROPAGATION_SUPPORTS encountering an existing
 	 * transaction) fails, the transaction will be globally marked as rollback-only.
 	 * The only possible outcome of such a transaction is a rollback: The
 	 * transaction originator <i>cannot</i> make the transaction commit anymore.

spring-tx/src/main/java/org/springframework/transaction/support/TransactionSynchronizationManager.java

@@ -443,7 +443,7 @@ public static void setActualTransactionActive(boolean active) {
 	 * between active transaction synchronization (with or without backing
 	 * resource transaction; also on PROPAGATION_SUPPORTS) and an actual
 	 * transaction being active (with backing resource transaction;
-	 * on PROPAGATION_REQUIRES, PROPAGATION_REQUIRES_NEW, etc).
+	 * on PROPAGATION_REQUIRED, PROPAGATION_REQUIRES_NEW, etc).
 	 * @see #isSynchronizationActive()
 	 */
 	public static boolean isActualTransactionActive() {