ByteUtils: improve JavaDoc comments for bigIntegerToBytes(), bytesToB…

…igInteger()

core/src/main/java/org/bitcoinj/base/internal/ByteUtils.java

@@ -64,21 +64,20 @@ public static byte[] parseHex(String string) {
 
     /**
      * <p>
-     * The regular {@link BigInteger#toByteArray()} includes the sign bit of the number and
-     * might result in an extra byte addition. This method removes this extra byte.
+     * The built-in {@link BigInteger#toByteArray()} includes the sign bit of the number and
+     * may result in an extra byte in cases of unsigned data. This method removes this extra byte.
      * </p>
      * <p>
-     * Assuming only positive numbers, it's possible to discriminate if an extra byte
-     * is added by checking if the first element of the array is 0 (0000_0000).
-     * Due to the minimal representation provided by BigInteger, it means that the bit sign
-     * is the least significant bit 0000_000<b>0</b> .
-     * Otherwise the representation is not minimal.
-     * For example, if the sign bit is 0000_00<b>0</b>0, then the representation is not minimal due to the rightmost zero.
+     * Assuming only positive numbers, it's possible to tell if an extra byte
+     * was added by checking if the first element of the array is 0 (0000_0000).
+     * Due to the guarantee of a minimal representation provided by BigInteger, we know that the sign bit
+     * will be the least significant bit 0000_000<b>0</b> of a zero-value first byte.
+     * Otherwise the representation would not be minimal.
      * </p>
-     * This is the antagonist to {@link #bytesToBigInteger(byte[])}.
-     * @param b the integer to format into a byte array
-     * @param numBytes the desired size of the resulting byte array
-     * @return numBytes byte long array.
+     * This is the inverse of {@link #bytesToBigInteger(byte[])}.
+     * @param b the non-negative integer to format into a byte array
+     * @param numBytes the maximum allowed size of the resulting byte array
+     * @return byte array of max length {@code numBytes}
      */
     public static byte[] bigIntegerToBytes(BigInteger b, int numBytes) {
         checkArgument(b.signum() >= 0, () -> "b must be positive or zero: " + b);
@@ -95,7 +94,7 @@ public static byte[] bigIntegerToBytes(BigInteger b, int numBytes) {
     }
 
     /**
-     * Converts an array of bytes into a positive BigInteger. This is the antagonist to
+     * Converts an array of bytes into a positive BigInteger. This is the inverse of
      * {@link #bigIntegerToBytes(BigInteger, int)}.
      *
      * @param bytes to convert into a BigInteger