Fix typos for validateExistingTransaction

Closes gh-36767

Signed-off-by: Yanming Zhou <zhouyanming@gmail.com>

(cherry picked from commit cfb8dc6)

Author: quaff

framework-docs/modules/ROOT/pages/data-access/transaction/declarative/tx-propagation.adoc

@@ -22,7 +22,7 @@ where all the underlying resources have to participate in the service-level tran
 
 NOTE: By default, a participating transaction joins the characteristics of the outer scope,
 silently ignoring the local isolation level, timeout value, or read-only flag (if any).
-Consider switching the `validateExistingTransactions` flag to `true` on your transaction
+Consider switching the `validateExistingTransaction` flag to `true` on your transaction
 manager if you want isolation level declarations to be rejected when participating in
 an existing transaction with a different isolation level. This non-lenient mode also
 rejects read-only mismatches (that is, an inner read-write transaction that tries to participate

spring-tx/src/main/java/org/springframework/transaction/TransactionDefinition.java

@@ -211,7 +211,7 @@ default int getPropagationBehavior() {
 	 * to match the values of the same constants on {@link java.sql.Connection}.
 	 * <p>Exclusively designed for use with {@link #PROPAGATION_REQUIRED} or
 	 * {@link #PROPAGATION_REQUIRES_NEW} since it only applies to newly started
-	 * transactions. Consider switching the "validateExistingTransactions" flag to
+	 * transactions. Consider switching the "validateExistingTransaction" flag to
 	 * "true" on your transaction manager if you'd like isolation level declarations
 	 * to get rejected when participating in an existing transaction with a different
 	 * isolation level.

spring-tx/src/main/java/org/springframework/transaction/annotation/Transactional.java

@@ -179,7 +179,7 @@
 	 * <p>Defaults to {@link Isolation#DEFAULT}.
 	 * <p>Exclusively designed for use with {@link Propagation#REQUIRED} or
 	 * {@link Propagation#REQUIRES_NEW} since it only applies to newly started
-	 * transactions. Consider switching the "validateExistingTransactions" flag to
+	 * transactions. Consider switching the "validateExistingTransaction" flag to
 	 * "true" on your transaction manager if you'd like isolation level declarations
 	 * to get rejected when participating in an existing transaction with a different
 	 * isolation level.

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

@@ -152,7 +152,7 @@ public final void setPropagationBehaviorName(String constantName) throws Illegal
 	 * in the TransactionDefinition interface. Default is PROPAGATION_REQUIRED.
 	 * <p>Exclusively designed for use with {@link #PROPAGATION_REQUIRED} or
 	 * {@link #PROPAGATION_REQUIRES_NEW} since it only applies to newly started
-	 * transactions. Consider switching the "validateExistingTransactions" flag to
+	 * transactions. Consider switching the "validateExistingTransaction" flag to
 	 * "true" on your transaction manager if you'd like isolation level declarations
 	 * to get rejected when participating in an existing transaction with a different
 	 * isolation level.
@@ -194,7 +194,7 @@ public final void setIsolationLevelName(String constantName) throws IllegalArgum
 	 * in the TransactionDefinition interface. Default is ISOLATION_DEFAULT.
 	 * <p>Exclusively designed for use with {@link #PROPAGATION_REQUIRED} or
 	 * {@link #PROPAGATION_REQUIRES_NEW} since it only applies to newly started
-	 * transactions. Consider switching the "validateExistingTransactions" flag to
+	 * transactions. Consider switching the "validateExistingTransaction" flag to
 	 * "true" on your transaction manager if you'd like isolation level declarations
 	 * to get rejected when participating in an existing transaction with a different
 	 * isolation level.