Refine null-safety in more modules

This commit refines the null-safety in:
 - spring-jdbc
 - spring-r2dbc
 - spring-orm
 - spring-beans
 - spring-aop

See gh-32475

spring-jdbc/src/main/java/org/springframework/jdbc/BadSqlGrammarException.java

@@ -19,6 +19,7 @@ package org.springframework.jdbc;
 import java.sql.SQLException;
 
 import org.springframework.dao.InvalidDataAccessResourceUsageException;
+import org.springframework.lang.Nullable;
 
 /**
  * Exception thrown when SQL specified is invalid. Such exceptions always have
@@ -52,6 +53,7 @@ public class BadSqlGrammarException extends InvalidDataAccessResourceUsageExcept
 	/**
 	 * Return the wrapped SQLException.
 	 */
+	@Nullable
 	public SQLException getSQLException() {
 		return (SQLException) getCause();
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/InvalidResultSetAccessException.java

@@ -64,6 +64,7 @@ public class InvalidResultSetAccessException extends InvalidDataAccessResourceUs
 	/**
 	 * Return the wrapped SQLException.
 	 */
+	@Nullable
 	public SQLException getSQLException() {
 		return (SQLException) getCause();
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/SQLWarningException.java

@@ -19,6 +19,7 @@ package org.springframework.jdbc;
 import java.sql.SQLWarning;
 
 import org.springframework.dao.UncategorizedDataAccessException;
+import org.springframework.lang.Nullable;
 
 /**
  * Exception thrown when we're not ignoring {@link java.sql.SQLWarning SQLWarnings}.
@@ -49,6 +50,7 @@ public class SQLWarningException extends UncategorizedDataAccessException {
 	 * Return the underlying {@link SQLWarning}.
 	 * @since 5.3.29
 	 */
+	@Nullable
 	public SQLWarning getSQLWarning() {
 		return (SQLWarning) getCause();
 	}
@@ -58,6 +60,7 @@ public class SQLWarningException extends UncategorizedDataAccessException {
 	 * @deprecated as of 5.3.29, in favor of {@link #getSQLWarning()}
 	 */
 	@Deprecated(since = "5.3.29")
+	@Nullable
 	public SQLWarning SQLWarning() {
 		return getSQLWarning();
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/UncategorizedSQLException.java

@@ -53,6 +53,7 @@ public class UncategorizedSQLException extends UncategorizedDataAccessException
 	/**
 	 * Return the underlying SQLException.
 	 */
+	@Nullable
 	public SQLException getSQLException() {
 		return (SQLException) getCause();
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/core/JdbcTemplate.java

@@ -907,11 +907,13 @@ public class JdbcTemplate extends JdbcAccessor implements JdbcOperations {
 
 	@Deprecated
 	@Override
+	@Nullable
 	public <T> T queryForObject(String sql, @Nullable Object[] args, Class<T> requiredType) throws DataAccessException {
 		return queryForObject(sql, args, getSingleColumnRowMapper(requiredType));
 	}
 
 	@Override
+	@Nullable
 	public <T> T queryForObject(String sql, Class<T> requiredType, @Nullable Object... args) throws DataAccessException {
 		return queryForObject(sql, args, getSingleColumnRowMapper(requiredType));
 	}

spring-jdbc/src/main/java/org/springframework/jdbc/support/incrementer/AbstractDataFieldMaxValueIncrementer.java

@@ -20,6 +20,7 @@ import javax.sql.DataSource;
 
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.dao.DataAccessException;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -34,9 +35,11 @@ import org.springframework.util.Assert;
  */
 public abstract class AbstractDataFieldMaxValueIncrementer implements DataFieldMaxValueIncrementer, InitializingBean {
 
+	@Nullable
 	private DataSource dataSource;
 
 	/** The name of the sequence/table containing the sequence. */
+	@Nullable
 	private String incrementerName;
 
 	/** The length to which a string result should be pre-pended with zeroes. */