Polish Javadoc

Update Javadoc to add missing @return and @param elements.

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/JavaAgentDetector.java

@@ -30,6 +30,7 @@ public interface JavaAgentDetector {
 	 * Returns {@code true} if {@code url} points to a Java agent jar file, otherwise
 	 * {@code false} is returned.
 	 * @param url The url to examine
+	 * @return if the URL points to a Java agent
 	 */
 	public boolean isJavaAgentJar(URL url);
 

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/CentralDirectoryEndRecord.java

@@ -115,6 +115,7 @@ class CentralDirectoryEndRecord {
 
 	/**
 	 * Return the number of ZIP entries in the file.
+	 * @return the number of records in the zip
 	 */
 	public int getNumberOfRecords() {
 		return (int) Bytes.littleEndianValue(this.block, this.offset + 10, 2);

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarEntry.java

@@ -44,6 +44,7 @@ public class JarEntry extends java.util.jar.JarEntry {
 
 	/**
 	 * Return the source {@link JarEntryData} that was used to create this entry.
+	 * @return the source of the entry
 	 */
 	public JarEntryData getSource() {
 		return this.source;
@@ -51,6 +52,8 @@ public class JarEntry extends java.util.jar.JarEntry {
 
 	/**
 	 * Return a {@link URL} for this {@link JarEntry}.
+	 * @return the URL for the entry
+	 * @throws MalformedURLException if the URL is not valid
 	 */
 	public URL getUrl() throws MalformedURLException {
 		return new URL(this.source.getSource().getUrl(), getName());

spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/util/SystemPropertyUtils.java

@@ -170,6 +170,7 @@ public abstract class SystemPropertyUtils {
 	 * provided key. Environment variables in <code>UPPER_CASE</code> style are allowed
 	 * where System properties would normally be <code>lower.case</code>.
 	 * @param key the key to resolve
+	 * @param defaultValue the default value
 	 * @param text optional extra context for an error message if the key resolution fails
 	 * (e.g. if System properties are not accessible)
 	 * @return a static property value or null of not found