Fix checkstyle errors

Author: agentgt

jooby/src/main/java/io/jooby/spi/ValueContainer.java

@@ -3,8 +3,15 @@
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
+import io.jooby.Value;
+
+/**
+ *  A restricted base type of {@link Value} for the {@link ValueConverter} SPI.
+ * @author agentgt
+ *
+ */
 public interface ValueContainer {
-  
+
   /**
    * Get a value at the given position.
    *
@@ -20,11 +27,21 @@ public interface ValueContainer {
    * @return Field value.
    */
   @Nonnull ValueContainer get(@Nonnull String name);
-  
+
+  /**
+   * Get string value.
+   *
+   * @return String value.
+   */
   @Nonnull String value();
-  
+
+  /**
+   * Convert this value to String (if possible) or <code>null</code> when missing.
+   *
+   * @return Convert this value to String (if possible) or <code>null</code> when missing.
+   */
   @Nullable String valueOrNull();
-  
+
   /**
    * True for missing values.
    *
@@ -38,7 +55,7 @@ public interface ValueContainer {
    * @return Number of values. Mainly for array and hash values.
    */
   int size();
-  
+
   /**
    * True if this value is an array/sequence (not single or hash).
    *

jooby/src/main/java/io/jooby/spi/ValueConverter.java

@@ -6,20 +6,28 @@
 import io.jooby.TypeMismatchException;
 import io.jooby.Value;
 
+/**
+ * An SPI for value conversion.
+ * @author agentgt
+ */
 public interface ValueConverter {
   /**
-   * This defaults to true to allow a functional interface.
-   * @param type
-   * @return
+   * A short circuit to see if the converter supports the given type.
+   *
+   * This defaults to true to allow a functional interface since convert can return null
+   * to indicate it does not support the type.
+   *
+   * @param type class or interface
+   * @return true if the converter can convert for the type
    */
   default boolean supportsType(@Nonnull Class<?> type) {
     return true;
   }
   /**
    * Converts values for {@link Value#to} and friends. Returning null indicates the type is not supported
    * or the converter chose not to do the conversion.
-   * @param value
-   * @param type
+   * @param value the value to be converted
+   * @param type the desired type. The type should be the equal or a super of the resulting instance returned.
    * @return <code>null</code> indicates that the converter chose to delegate to other converters down the chain.
    * @throws TypeMismatchException if the converter cannot convert the type and does not want to delegate.
    */

jooby/src/main/java/io/jooby/spi/ValueConverters.java

@@ -7,24 +7,45 @@
 
 import io.jooby.TypeMismatchException;
 
+/**
+ * Contains the {@link ValueConverter}s loaded via the ServiceLoader. It is is a
+ * singleton and an instance can be retrieved with {@link #getInstance()}. The
+ * ValueConverters are stored in an ordered collection and thus resolution of
+ * type to be converted is based on the order of the converters.
+ *
+ * @author agentgt
+ *
+ */
 public final class ValueConverters {
+
   // Allow thread safe adding of ValueConverters.
   private final CopyOnWriteArrayList<ValueConverter> valueConverters;
-  
+
   // Initialization on demand
   private static final class Hidden {
+
     private static final ValueConverters INSTANCE = ValueConverters.create().fromServiceLoader();
   }
-  
+
   private ValueConverters(CopyOnWriteArrayList<ValueConverter> valueConverters) {
     super();
     this.valueConverters = valueConverters;
   }
-  
+
   static ValueConverters create() {
     return new ValueConverters(new CopyOnWriteArrayList<>());
   }
-  
+
+  /**
+   * Attempts to convert values to an object based on the provided type.
+   *
+   * @param v
+   *          value
+   * @param c
+   *          desired type
+   * @return the type if converted or null if conversion was not possible.
+   * @throws TypeMismatchException failure in a converter
+   */
   public @Nullable Object convert(ValueContainer v, Class<?> c) throws TypeMismatchException {
     Object result = null;
     for (ValueConverter vc : valueConverters) {
@@ -37,33 +58,37 @@ static ValueConverters create() {
     }
     return result;
   }
-  
-  final ValueConverters fromServiceLoader() {
+
+  ValueConverters fromServiceLoader() {
     ServiceLoader<ValueConverter> sl = ServiceLoader.load(ValueConverter.class);
-    //If any failes to load we will fail entirely.
-    //The value converters found earlier in the classpath take precedence.
+    // If any failes to load we will fail entirely.
+    // The value converters found earlier in the classpath take precedence.
     sl.forEach(this::add);
     return this;
   }
+
   /**
-   * You can add value converters programmatic. For now its protected.
-   * Its also to aid unit testing since serviceloader is inherently static singleton.
+   * You can add value converters programmatic. For now its protected. Its also
+   * to aid unit testing since serviceloader is inherently static singleton.
+   *
    * @param vc
    * @return
    */
-  /* private */ final ValueConverters add(ValueConverter vc) {
+  /* private */ ValueConverters add(ValueConverter vc) {
     valueConverters.add(vc);
     return this;
   }
-  
-  final ValueConverters clear() {
+
+  ValueConverters clear() {
     valueConverters.clear();
     return this;
   }
-  
-  
-  
-  public static final ValueConverters getInstance() {
+
+  /**
+   * The ValueConverters singleton usually preloaded by the ServiceLoader.
+   * @return the shared singleton used by Jooby
+   */
+  public static ValueConverters getInstance() {
     return ValueConverters.Hidden.INSTANCE;
   }