8023022: Some more typos in javadoc

Reviewed-by: lancea, alanb

jdk/src/share/classes/com/sun/org/apache/xml/internal/security/algorithms/SignatureAlgorithm.java

@@ -296,7 +296,7 @@ public class SignatureAlgorithm extends Algorithm {
      * which is executed on the internal {@link java.security.Signature} object.
      *
      * @param signature
-     * @return true if if the signature is valid.
+     * @return true if the signature is valid.
      *
      * @throws XMLSignatureException
      */

jdk/src/share/classes/java/lang/Thread.java

@@ -973,7 +973,7 @@ class Thread implements Runnable {
      * @deprecated This method was originally designed to destroy this
      *     thread without any cleanup. Any monitors it held would have
      *     remained locked. However, the method was never implemented.
-     *     If if were to be implemented, it would be deadlock-prone in
+     *     If it were to be implemented, it would be deadlock-prone in
      *     much the manner of {@link #suspend}. If the target thread held
      *     a lock protecting a critical system resource when it was
      *     destroyed, no thread could ever access this resource again.

jdk/src/share/classes/javax/sql/rowset/RowSetMetaDataImpl.java

@@ -579,7 +579,7 @@ public class RowSetMetaDataImpl implements RowSetMetaData,  Serializable {
      *
      * @param columnIndex the first column is 1, the second is 2, and so on;
      *        must be between <code>1</code> and the number of columns, inclusive
-     * @return <code>true</code> if if a value in the designated column is a signed
+     * @return <code>true</code> if a value in the designated column is a signed
      *         number; <code>false</code> otherwise
      * @throws SQLException if a database access error occurs
      *         or the given column number is out of bounds

jdk/src/share/classes/javax/swing/JViewport.java

@@ -661,7 +661,7 @@ public class JViewport extends JComponent implements Accessible
      * painting to originate from {@code JViewport}, or one of its
      * ancestors. Otherwise returns {@code false}.
      *
-     * @return true if if scroll mode is a {@code BACKINGSTORE_SCROLL_MODE}.
+     * @return true if scroll mode is a {@code BACKINGSTORE_SCROLL_MODE}.
      * @see JComponent#isPaintingOrigin()
      */
     protected boolean isPaintingOrigin() {

jdk/src/share/classes/sun/font/GlyphList.java

@@ -148,7 +148,7 @@ public final class GlyphList {
      * throughput on a MP system. If for some reason the reusable
      * GlyphList is checked out for a long time (or never returned?) then
      * we would end up always creating new ones. That situation should not
-     * occur and if if did, it would just lead to some extra garbage being
+     * occur and if it did, it would just lead to some extra garbage being
      * created.
      */
     private static GlyphList reusableGL = new GlyphList();

jdk/src/share/classes/sun/misc/SoftCache.java

@@ -309,7 +309,7 @@ public class SoftCache extends AbstractMap<Object, Object> implements Map<Object
      *                mapped
      *
      * @return  The previous value to which this key was mapped, or
-     *          <code>null</code> if if there was no mapping for the key
+     *          <code>null</code> if there was no mapping for the key
      */
     public Object put(Object key, Object value) {
         processQueue();