Remove invalid javadoc links

Links were removed due to following reasons: dependency commons-lang3 not containing docs sources; package sun.reflect.Reflection was deprecated and removed in JDK8

Author: lukaszspyra

log4j-core/src/main/java/org/apache/logging/log4j/core/impl/ExtendedClassInfo.java

@@ -38,7 +38,7 @@ public final class ExtendedClassInfo implements Serializable {
     /**
      * Constructs a new instance.
      *
-     * @param exact Whether the class was obtained via {@link sun.reflect.Reflection#getCallerClass(int)}.
+     * @param exact Whether the class was obtained via {@code sun.reflect.Reflection#getCallerClass(int)}.
      * @param location a classpath element or a jar
      * @param version the string describing a version
      */

log4j-core/src/main/java/org/apache/logging/log4j/core/impl/ExtendedStackTraceElement.java

@@ -28,7 +28,7 @@
  * Complements a StackTraceElement with:
  * </p>
  * <ul>
- * <li>exact: whether the class was obtained via {@link sun.reflect.Reflection#getCallerClass(int)}</li>
+ * <li>exact: whether the class was obtained via {@code sun.reflect.Reflection#getCallerClass(int)}</li>
  * <li>location: a classpath element or a jar</li>
  * <li>version</li>
  * </ul>

log4j-core/src/main/java/org/apache/logging/log4j/core/util/datetime/FastDateParser.java

@@ -392,7 +392,8 @@ public Object parseObject(final String source, final ParsePosition pos) {
      * given by {@link ParsePosition#getIndex()} has been updated. If the input buffer has been fully
      * parsed, then the index will point to just after the end of the input buffer.
      *
-     * @see org.apache.commons.lang3.time.DateParser#parse(java.lang.String, java.text.ParsePosition)
+     * @see <a href="https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/time/DateParser.html#parse-java.lang.String-java.text.ParsePosition-">
+     *     org.apache.commons.lang3.time.DateParser#parse(String, ParsePosition)</a>
      */
     @Override
     public Date parse(final String source, final ParsePosition pos) {