Simplified toString() for duration

Previously it normalized duration in order to expose a more
human-friendly string. For example, 7 days would become a week,
12 months would become a year. It seems nice but might create a
false impression that it is possible to retrieve weeks and years
from an `IsoDuration` object. However, it only supports months,
days, seconds and nanoseconds. Also, other drivers do not normalize
durations.

This commit makes `IsoDuration#toString()` simply concatenate all
values into a string as is. Resulting string will only contain months,
days, seconds and nanoseconds. Zero values are not filtered out. So
returned ISO strings represent exactly same durations but in different
format.

Author: lutovich

driver/src/main/java/org/neo4j/driver/internal/InternalIsoDuration.java

@@ -38,8 +38,6 @@
 public class InternalIsoDuration implements IsoDuration
 {
     private static final List<TemporalUnit> SUPPORTED_UNITS = unmodifiableList( asList( MONTHS, DAYS, SECONDS, NANOS ) );
-    private static final InternalIsoDuration ZERO = new InternalIsoDuration( 0, 0, 0, 0 );
-    public static final long NANOS_PER_SECOND = 1_000_000_000L;
 
     private final long months;
     private final long days;
@@ -195,65 +193,6 @@ public int hashCode()
     @Override
     public String toString()
     {
-        // print the duration in iso standard format.
-        if ( this.equals( ZERO ) )
-        {
-            return "PT0S"; // no need to allocate a string builder if we know the result
-        }
-        StringBuilder str = new StringBuilder().append( "P" );
-        append( str, months / 12, 'Y' );
-        append( str, months % 12, 'M' );
-        append( str, days / 7, 'W' );
-        append( str, days % 7, 'D' );
-        if ( seconds != 0 || nanoseconds != 0 )
-        {
-            str.append( 'T' );
-            long s = seconds % 3600;
-            append( str, seconds / 3600, 'H' );
-            append( str, s / 60, 'M' );
-            s %= 60;
-            if ( s != 0 )
-            {
-                str.append( s );
-                if ( nanoseconds != 0 )
-                {
-                    nanos( str );
-                }
-                str.append( 'S' );
-            }
-            else if ( nanoseconds != 0 )
-            {
-                if ( nanoseconds < 0 )
-                {
-                    str.append( '-' );
-                }
-                str.append( '0' );
-                nanos( str );
-                str.append( 'S' );
-            }
-        }
-        if ( str.length() == 1 )
-        { // this was all zeros (but not ZERO for some reason), ensure well formed output:
-            str.append( "T0S" );
-        }
-        return str.toString();
-    }
-
-    private static void append( StringBuilder str, long quantity, char unit )
-    {
-        if ( quantity != 0 )
-        {
-            str.append( quantity ).append( unit );
-        }
-    }
-
-    private void nanos( StringBuilder str )
-    {
-        str.append( '.' );
-        int n = nanoseconds < 0 ? -nanoseconds : nanoseconds;
-        for ( int mod = (int)NANOS_PER_SECOND; mod > 1 && n > 0; n %= mod )
-        {
-            str.append( n / (mod /= 10) );
-        }
+        return String.format( "P%sM%sDT%s.%sS", months, days, seconds, String.format( "%09d", nanoseconds ) );
     }
 }

driver/src/test/java/org/neo4j/driver/internal/InternalIsoDurationTest.java

@@ -156,13 +156,17 @@ public void shouldCreateFromDuration()
     @Test
     public void toStringShouldPrintInIsoStandardFormat() throws Throwable
     {
-        assertThat( new InternalIsoDuration( 0, 0, 0, 0 ).toString(), equalTo( "PT0S" ) );
-        assertThat( new InternalIsoDuration( Period.parse( "P356D" ) ).toString(), equalTo( "P50W6D" ) );
-        assertThat( new InternalIsoDuration( Duration.parse( "PT45S" ) ).toString(), equalTo( "PT45S" ) );
+        assertThat( new InternalIsoDuration( 0, 0, 0, 0 ).toString(), equalTo( "P0M0DT0.000000000S" ) );
+        assertThat( new InternalIsoDuration( 2, 45, 59, 11 ).toString(), equalTo( "P2M45DT59.000000011S" ) );
+        assertThat( new InternalIsoDuration( 4, -101, 1, 999 ).toString(), equalTo( "P4M-101DT1.000000999S" ) );
+        assertThat( new InternalIsoDuration( -1, 12, -19, 1 ).toString(), equalTo( "P-1M12DT-19.000000001S" ) );
 
-        assertThat( new InternalIsoDuration( Period.parse( "P14D" ), Duration.parse( "PT16H12M" ) ).toString(), equalTo( "P2WT16H12M" ) );
-        assertThat( new InternalIsoDuration( Period.parse( "P5M1D" ), Duration.parse( "PT12H" ) ).toString(), equalTo( "P5M1DT12H" ) );
-        assertThat( new InternalIsoDuration( Period.parse( "P2W3D" ), Duration.parse( "PT12H" ) ).toString(), equalTo( "P2W3DT12H" ) );
+        assertThat( new InternalIsoDuration( Period.parse( "P356D" ) ).toString(), equalTo( "P0M356DT0.000000000S" ) );
+        assertThat( new InternalIsoDuration( Duration.parse( "PT45S" ) ).toString(), equalTo( "P0M0DT45.000000000S" ) );
+
+        assertThat( new InternalIsoDuration( Period.parse( "P14D" ), Duration.parse( "PT16H12M" ) ).toString(), equalTo( "P0M14DT58320.000000000S" ) );
+        assertThat( new InternalIsoDuration( Period.parse( "P5M1D" ), Duration.parse( "PT12H" ) ).toString(), equalTo( "P5M1DT43200.000000000S" ) );
+        assertThat( new InternalIsoDuration( Period.parse( "P2W3D" ), Duration.parse( "PT2H0.111222333S" ) ).toString(), equalTo( "P0M17DT7200.111222333S" ) );
     }
 
     private static IsoDuration newDuration( long months, long days, long seconds, int nanoseconds )