Internal refactoring

Author: garydgregory

src/main/java/org/apache/commons/io/input/ReaderInputStream.java

@@ -143,7 +143,7 @@ public Builder() {
          */
         @Override
         public ReaderInputStream get() throws IOException {
-            return new ReaderInputStream(getReader(), charsetEncoder, getBufferSize());
+            return new ReaderInputStream(this);
         }
 
         CharsetEncoder getCharsetEncoder() {
@@ -220,6 +220,11 @@ private static CharsetEncoder newEncoder(final Charset charset) {
 
     private boolean endOfInput;
 
+    @SuppressWarnings("resource") // caller closes.
+    private ReaderInputStream(final Builder builder) throws IOException {
+        this(builder.getReader(), builder.charsetEncoder, builder.getBufferSize());
+    }
+
     /**
      * Constructs a new {@link ReaderInputStream} that uses the virtual machine's {@link Charset#defaultCharset() default charset} with a default input buffer
      * size of {@value IOUtils#DEFAULT_BUFFER_SIZE} characters.