Refactor PageableExecutionUtils.

Closes #3103
Original pull request #3113

Author: erie0210

src/main/java/org/springframework/data/support/PageableExecutionUtils.java

@@ -31,6 +31,7 @@
  * @author Oliver Gierke
  * @author Christoph Strobl
  * @author Jens Schauder
+ * @author Jay Lee
  * @since 2.4
  */
 public abstract class PageableExecutionUtils {
@@ -54,19 +55,30 @@ public static <T> Page<T> getPage(List<T> content, Pageable pageable, LongSuppli
 		Assert.notNull(pageable, "Pageable must not be null");
 		Assert.notNull(totalSupplier, "TotalSupplier must not be null");
 
-		if (pageable.isUnpaged() || pageable.getOffset() == 0) {
-
-			if (pageable.isUnpaged() || pageable.getPageSize() > content.size()) {
-				return new PageImpl<>(content, pageable, content.size());
-			}
+		if (pageable.isUnpaged()) {
+			return new PageImpl<>(content, pageable, content.size());
+		}
 
-			return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
+		if (isFirstPage(pageable) && isPartialPage(content, pageable)) {
+			return new PageImpl<>(content, pageable, content.size());
 		}
 
-		if (content.size() != 0 && pageable.getPageSize() > content.size()) {
+		if (isSubsequentPage(pageable) && !content.isEmpty() && isPartialPage(content, pageable)) {
 			return new PageImpl<>(content, pageable, pageable.getOffset() + content.size());
 		}
 
 		return new PageImpl<>(content, pageable, totalSupplier.getAsLong());
 	}
+
+	private static <T> boolean isPartialPage(List<T> content, Pageable pageable) {
+		return pageable.getPageSize() > content.size();
+	}
+
+	private static boolean isFirstPage(Pageable pageable) {
+		return pageable.getOffset() == 0;
+	}
+
+	private static boolean isSubsequentPage(Pageable pageable) {
+		return !isFirstPage(pageable);
+	}
 }